Abstract:

Provided are elastomeric compositions, such as a tire innerliner,
comprising at least one isobutylene based elastomer and at least one
hydrocarbon fluid additive ("HFA"). The compositions have improved cold
temperature properties and are particularly useful as tire innerliners
for an aircraft tire. The use of a HFA in the elastomeric composition may
allow for the use of reduced amounts of secondary elastomers, such as
natural rubber, while allowing for an improved balance in the
composition's brittleness and permeability properties. Examples of useful
HFAs include polyalphaolefins, high purity hydrocarbon fluids, and water
white group III mineral oils.

Claims:

1. A cured elastomeric composition for use in a tire innerliner,
comprising:a. from 50 to 100 phr of at least one isobutylene-based
elastomer;b. less than or equal to 50 phr of natural rubber; andc. from 1
to 30 phr of at least one hydrocarbon fluid additive, wherein the
hydrocarbon fluid additive has a flash point of at least 200.degree. C.,
a pour point of less than or equal to -15.degree. C., and specific
gravity at 15.6.degree. C. of less than or equal to 0.880;wherein the
cured elastomeric composition has a MOCON permeability coefficient of
less than or equal to T, where T=-0.1147Y+0.54 where Y is the change in
brittleness determined by subtracting the brittleness in ° C. of
the cured elastomeric composition containing the hydrocarbon fluid
additive from the brittleness in ° C. of a cured composition
having the same components except that it contains a naphthenic oil
having a flash point in the range of 160 to 170.degree. C., a pour point
of about -40.degree. C..+-.5%, and a specific gravity at 15.6.degree. C.
of about 0.91.+-.0.01 instead of the hydrocarbon fluid additive.

3. The cured elastomeric composition of claim 1, wherein the composition
comprises less than or equal to 10 phr of natural rubber.

4. The cured composition of claim 1, wherein the hydrocarbon fluid
additive is selected from a group consisting of polyalphaolefins, high
purity hydrocarbon fluids, water white group III mineral oils, and blends
thereof.

5. The cured elastomeric composition of claim 1, wherein the hydrocarbon
fluid additive is a polyalphaolefin having a Kinematic viscosity at
100.degree. C. of at least 4 cSt.

6. The cured elastomeric composition of claim 1, wherein the hydrocarbon
fluid additive is a polyalphaolefin having a Kinematic viscosity at
100.degree. C. in the range of 6 to 40 cSt.

7. The cured elastomeric composition of claim 1, wherein the hydrocarbon
fluid additive is a polyalphaolefin having a viscosity index of at least
120.

10. The cured elastomeric composition of claim 1, wherein the composition
is a tire innerliner suitable for use in an aircraft tire.

11. A cured elastomeric composition for use in a tire innerliner,
comprising:a. from 50 to 90 phr of at least one isobutylene-based
elastomer;b. from 1 to 50 phr of natural rubber; andc. from 1 to 30 phr
of at least one hydrocarbon fluid additive, wherein the hydrocarbon fluid
additive has a flash point of at least 200.degree. C., a pour point of
less than or equal to -15.degree. C., and specific gravity at
15.6.degree. C. of less than or equal to 0.880;wherein the cured
elastomeric composition has a MOCON permeability coefficient of less than
or equal to Z, where Z=0.282X+0.4817 where X is the amount of natural
rubber in phr, and wherein the cured elastomeric composition has a
brittleness of less than or equal to A, where A=-0.13X-51 where X is the
amount of natural rubber in phr.

12. The cured elastomeric composition of claim 11, wherein the composition
comprises from 70 to 90 phr of the isobutylene-based elastomer.

14. The cured elastomeric composition of claim 11, wherein the composition
comprises from 10 to 30 phr of natural rubber.

15. The cured composition of claim 11, wherein the hydrocarbon fluid
additive is selected from a group consisting of polyalphaolefins, high
purity hydrocarbon fluids, water white group III mineral oils, and blends
thereof.

16. The cured elastomeric composition of claim 11, wherein the hydrocarbon
fluid additive is a polyalphaolefin having a Kinematic viscosity at
100.degree. C. of at least 4 cSt.

17. The cured elastomeric composition of claim 11, wherein the hydrocarbon
fluid additive is a polyalphaolefin having a Kinematic viscosity at
100.degree. C. in the range of 6 to 40 cSt.

18. The cured elastomeric composition of claim 11, wherein the hydrocarbon
fluid additive is a polyalphaolefin having a viscosity index of at least
120.

21. The cured elastomeric composition of claim 11, wherein the composition
is a tire innerliner suitable for use in an aircraft tire.

22. A process for producing an air barrier comprising the steps of:a.
combining from 50 to 90 phr of at least one isobutylene-based elastomer,
from 1 to 50 phr of natural rubber, and from 1 to 30 phr of at least one
hydrocarbon fluid additive, wherein the hydrocarbon fluid additive has a
flash point of at least 200.degree. C., a pour point of less than or
equal to -15.degree. C., and specific gravity at 15.6.degree. C. of less
than or equal to 0.880;b. curing the combined components to form a cured
elastomeric composition wherein the cured elastomeric composition has a
MOCON permeability coefficient of less than or equal to Z, where
Z=0.282X+0.4817 where X is the amount of natural rubber in phr, and
wherein the cured elastomeric composition has a brittleness of less than
or equal to A, where A=-0.13X-51 where X is the amount of natural rubber
in phr; andc. shaping the cured elastomeric composition to form the air
barrier.

23. The process of claim 22, wherein the air barrier is an innerliner
suitable for use in an aircraft tire.

24. An aircraft tire comprising an innerliner which comprises:a. from 50
to 90 phr of at least one isobutylene-based elastomer;b. from 1 to 50 phr
of natural rubber; andc. from 1 to 30 phr of at least one hydrocarbon
fluid additive, wherein the hydrocarbon fluid additive has a flash point
of at least 200.degree. C., a pour point of less than or equal to
-15.degree. C., and specific gravity at 15.6.degree. C. of less than or
equal to 0.880;wherein the aircraft tire has a MOCON permeability
coefficient of less than or equal to Z, where Z=0.282X+0.4817 where X is
the amount of natural rubber in phr, and wherein the cured elastomeric
composition has a brittleness of less than or equal to A, where
A=-0.13X-51 where X is the amount of natural rubber in phr.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001]This application is a continuation-in-part and claims the benefit of
priority from U.S. patent application Ser. No. 11/323,747, filed on Dec.
30, 2005 the disclosure of which is herein incorporated by reference.
U.S. patent application Ser. No. 11/323,747 is (a) a continuation-in-part
of U.S. patent application Ser. No. 10/518,886, filed Dec. 21, 2004,
which is a National Stage Application of International Application No.
PCT/US2003/016947, filed May 30, 2003, which claims the benefit of
Provisional Application No. 60/396,497, filed Jul. 17, 2002; and (b) a
continuation-in-part of Ser. No. 10/398,255, filed Apr. 3, 2003, which is
a National Stage Application of International Application No.
PCT/US2001/42767, filed Oct. 16, 2001, which claims the benefit of
Provisional Application No. 60/294,808, filed May 31, 2001, and is a
continuation-in-part of Ser. No. 09/691,764, filed Oct. 18, 2000, now
U.S. Pat. No. 6,710,116; the disclosures of which are all incorporated
herein by reference.

[0003]This invention relates to tire innerliners having improved cold
temperature properties. More particularly, this invention relates to
cured elastomeric compositions for use as tire innerliners that have
improved cold temperature properties and comprise a hydrocarbon fluid
additive.

BACKGROUND OF THE INVENTION

[0004]Elastomeric compositions are used in a wide variety of applications,
including hoses, belts, footwear components, vibration isolation devices,
tires, and tire components such as treads, sidewalls, and innerliners.
The selection of ingredients for the commercial formulation of an
elastomeric composition depends upon the balance of properties desired,
the application, and the application's end use. For example, in the tire
industry the balance between processing properties of the green (uncured)
composition in the tire plant and in-service performance of the cured
rubber tire composite is of particular importance. An additional
consideration to be balanced is the nature of the tire, e.g., bias versus
radial tire or passenger car tire versus truck tire versus aircraft tire.
The ability to improve a tire's air impermeability properties and flex
fatigue properties without affecting the processability of the uncured
elastomeric composition or while maintaining or improving the physical
property performance of the cured elastomeric composition is a goal that
still remains.

[0005]Generally, the raw ingredients and materials used in tire
compounding impact tire performance variables. Thus, any alternative to
conventional ingredients must be compatible with the rubbers, not
interfere with the vulcanization rate, be easily dispersed in all tire
compounds, be cost effective, and not adversely impact tire performance.
This is of particular concern for tire innerliners and tire innertubes
where performance properties must be maintained within specified
tolerance levels. For example, small increases in a tire innerliner
compound's 300% modulus can lead to reduction in fatigue resistance and
cracks with consequential loss in tire durability. Furthermore, for an
elastomeric composition that acts as an air barrier it is of particular
importance that any benefits in compound processability are not to the
detriment of the composition's air retention capabilities.

[0006]Conventionally, halobutyl rubbers have been used to obtain better
air-retention in tires. While halobutyl rubber has allowed for
improvement in a composition's air-retention qualities, it can negatively
effect the composition's flex fatigue and brittleness properties. This is
of particular concern for certain tire applications which require
improved heat resistance and improved cold temperature properties, such
as is required for race-car tires, snow tires, and aircraft tires. In
order to improve flex fatigue and brittleness properties, secondary
elastomers, such as ethylene-propylene rubber ("EP"),
ethylene-propylene-diene rubber ("EPDM"), or natural rubber, have been
blended with butyl rubbers in tire innerliner/innertube compounds. While
these secondary elastomers may help improve flex fatigue and brittleness
temperatures, the blending of EP, EPDM, or natural rubbers often
increases the air permeability of the elastomeric composition.

[0007]Thus, there is still a need for an elastomeric composition that is
suitable for a tire innerliner or tire innertube that will have enhanced
thermal stability and physical properties under severe temperature and
operating conditions such as required for race car tires and aircraft
tires. It would be advantageous to have an elastomeric composition that
possesses improved low-temperature toughness without sacrificing other
advantageous traits such as improved processability and
air-impermeability.

SUMMARY OF THE INVENTION

[0008]The present disclosure provides an elastomeric composition, such as
a tire innerliner, comprising at least one isobutylene based elastomer
and at least one hydrocarbon fluid additive ("HFA"). The compositions are
useful in a variety of applications and are particularly suitable for an
air barrier such as a tire innertube or innerliner. In some embodiments,
the composition provides improved cold temperature properties and is
particularly useful as a tire innerliner for an aircraft tire.

[0009]In one aspect this disclosure relates to a cured elastomeric
composition for use in a tire innerliner, comprising (i) from 50 to 100
phr of at least one isobutylene-based elastomer; (ii) less than or equal
to 50 phr, or less than or equal to 10 phr, of natural rubber; and (iii)
from 1 to 30 phr of at least one HFA. The cured elastomeric composition
preferably has a MOCON permeability coefficient of less than or equal to
T, where T=-0.1147Y+0.54 where Y is the change in brittleness determined
by subtracting the brittleness in ° C. of the cured elastomeric
composition containing HFA from the brittleness in ° C. of a cured
composition having the same components except that it contains a
naphthenic oil having a flash point in the range of 160 to 170°
C., a pour point of about -40° C.±5%, and a specific gravity at
15.6° C. of about 0.91±0.01 instead of the HFA.

[0010]In another aspect this disclosure relates to a cured elastomeric
composition for use in a tire innerliner, comprising (i) from 50 to 90
phr, or from 70 to 90 phr, of at least one isobutylene-based elastomer;
(ii) from 1 to 50 phr, or from 10 to 30 phr, or from 15 to 30 phr, of
natural rubber; and (iii) from 1 to 30 phr, or from 4 to 30 phr, of at
least one HFA. The cured elastomeric composition preferably has a MOCON
permeability coefficient of less than or equal to Z, where
Z=0.282X+0.4817 where X is the amount of natural rubber in phr. The cured
elastomeric composition preferably has a brittleness of less than or
equal to A, where A=-0.13X-51 where X is the amount of natural rubber in
phr.

[0011]In yet another aspect this disclosure relates to a process for
producing an air barrier comprising the steps of (i) combining from 50 to
90 phr of at least one isobutylene-based elastomer, from 1 to 50 phr (or
from 10 to 50 phr) of natural rubber, and from 1 to 30 phr (or from 4 to
30 phr) of at least one HFA; (ii) curing the combined components to form
a cured elastomeric composition wherein the cured elastomeric composition
has a MOCON permeability coefficient of less than or equal to Z, where
Z=0.282X+0.4817 where X is the amount of natural rubber in phr and a
brittleness of less than or equal to A, where A=-0.13X-51 where X is the
amount of natural rubber in phr; and (iii) shaping the cured elastomeric
composition to form the air barrier.

[0012]In one embodiment, and in combination with any of the above
disclosed aspects or embodiments, the isobutylene-based elastomer is
selected from the group consisting of butyl rubber, halogenated butyl
rubber, star-branched butyl rubber, halogenated star-branched butyl
rubber, poly(isobutylene-co-p-methylstyrene), halogenated
poly(isobutylene-co-p-methylstyrene), and mixtures thereof.

[0013]In another embodiment, and in combination with any of the above
disclosed aspects or embodiments, the HFA has a flash point of at least
200° C., a pour point of less than or equal to -15° C., and
a specific gravity at 15.6° C. of less than or equal to 0.880.

[0014]In one embodiment and in combination with any of the above disclosed
aspects or embodiments, the hydrocarbon fluid additive is selected from a
group consisting of polyalphaolefins, high purity hydrocarbon fluids,
water white group III mineral oils, and blends thereof.

[0015]In one embodiment and in combination with any of the above disclosed
aspects or embodiments, the HFA is a polyalphaolefin and has a Kinematic
viscosity at 100° C. of at least 4 cSt, or in the range of 6 to 40
cSt. The polyalphaolefin may also have a viscosity index of at least 120.

[0016]In some embodiments, and in combination with any of the above
disclosed aspects or embodiments, the elastomeric composition is
substantially free of naphthenic oil and/or is substantially free of
aromatic oil.

[0017]In other embodiments, and in combination with any of the above
disclosed aspects or embodiments, the elastomeric composition further
comprises one or more filler components selected from calcium carbonate,
mica, silica, silicates, talc, titanium dioxide, starch, wood flour,
carbon black, and mixtures thereof.

[0018]These and other objects, features, and advantages will become
apparent as reference is made to the following detailed description,
preferred embodiments, examples, and appended claims.

BRIEF DESCRIPTION OF THE FIGURE

[0019]FIG. 1 is a graph illustrating the impact on an elastomeric
composition's brittleness when the composition contains polyalphaolefin
("PAO") and varying amounts of natural rubber.

[0020]FIG. 2 is a graph illustrating the impact on an elastomeric
composition's permeability when the composition contains PAO and varying
amounts of natural rubber.

[0021]FIG. 3 is a graph illustrating the improvement in an elastomeric
composition's brittleness/permeability balance that is obtained when the
composition comprises PAO.

DETAILED DESCRIPTION OF THE INVENTION

[0022]Various specific embodiments, versions, and examples are described
herein, including exemplary embodiments and definitions that are adopted
for purposes of understanding the claimed invention. While the following
detailed description gives specific preferred embodiments, those skilled
in the art will appreciate that these embodiments are exemplary only, and
that the invention can be practiced in other ways. For purposes of
determining infringement, the scope of the invention will refer to any
one or more of the appended claims, including their equivalents, and
elements or limitations that are equivalent to those that are recited.
Any reference to the "invention" may refer to one or more, but not
necessarily all, of the inventions defined by the claims.

[0023]The term "phr" means parts per hundred parts of rubber, and is a
measure common in the art wherein components of a composition are
measured relative to the total of all of the elastomer (rubber)
components. The total phr or parts for all rubber components, whether
one, two, three, or more different rubber components is present in a
given recipe is defined as 100 phr. All other non-rubber components are
ratioed against the 100 parts of rubber and are expressed in phr.

[0024]The term "elastomer," as used herein, refers to any polymer or
combination of polymers consistent with the ASTM D1566 definition of "a
material that is capable of recovering from large deformations, and can
be, or already is, modified to a state in which it is essentially
insoluble (but can swell) in boiling solvent." As used herein, the term
"elastomer" may be used interchangeably with the term "rubber." Preferred
elastomers have a melting point that cannot be measured by DSC or if it
can be measured by DSC is less than 40° C., or preferably less
than 20° C., or less than 0° C. Preferred elastomers have a
Tg of -50° C. or less as measured by DSC.

[0025]As used herein, the term "isobutylene based elastomer," refers to an
elastomer or polymer comprising at least 70 mol % repeat units from
isobutylene.

[0026]The elastomeric compositions of the invention comprise isobutylene
based elastomers, hydrocarbon fluid additives ("HFA"), and may further
comprise various other fillers and additives. In one embodiment, the HFA
is used in addition to other conventional processing aids or oils.
However, in other embodiments, the HFA may be able to partially or fully
replace conventional processing aids and/or oil, while maintaining
current tire performance parameters within an acceptable range. For
example, the use of HFA in place of aromatic process oils may allow for
optimization of the tire innerliners impermeability and brittleness
properties. Alternatively, the HFA may be blended with a naphthenic or
paraffinic process oil to maintain tire performance parameters equivalent
to those compositions containing only aromatic oil.

[0027]A thermal gravimetric analyzer with headspace gas chromatography may
be used to analyze the content and composition of oil additives in the
elastomeric composition. The amount of HFA in the elastomeric composition
may be determined as described in Paragraphs [0623] to [0630] in U.S.
Patent Application Publication No. 2008/0045638, herein incorporated by
reference.

[0028]In one embodiment, the elastomeric composition is substantially free
of naphthenic oil. Substantially free of naphthenic oils is defined to
mean that naphthenic oil has not deliberately been added to the
elastomeric composition, or, in the alternative, if present the
elastomeric composition comprises less than 2 phr of naphthenic oil, or
less than 0.5 phr, or more preferably less than 0.25 phr, or most
preferably less than 0.1 phr of naphthenic oil. In one embodiment,
naphthenic oil is present at 0 phr. Naphthenic oils are typically heavy
hydrogenated oils having greater than 40% of the carbons in naphthenic
structures (i.e., saturated rings) and less than 20% of the carbons in
aromatic structures (i.e., unsaturated rings). Some naphthenic oils have
about 40-55% of the carbons in paraffinic chain-like structures (i.e.,
isoparaffinic and normal paraffinic), 40-55% of the carbons in naphthenic
structures, and 6-15% of the carbons in aromatic structures. As used
herein, for the purpose of comparing an elastomeric structure containing
HFA to another composition having the same components except that it
contains a naphthenic oil instead of the HFA, the naphthenic oil has a
flash point in the range of 160 to 170° C., a pour point of about
-40° C.±5%, and a specific gravity at 15.6° C. of about
0.91±0.01.

[0029]In another embodiment, the elastomeric composition is substantially
free of aromatic oil. Substantially free of aromatic oil is defined to
mean that aromatic oil has not deliberately been added to the elastomeric
composition, or, in the alternative, if present the elastomeric
composition comprises less than 2 phr of aromatic oil, or less than 0.5
phr, or more preferably less than 0.25 phr, or most preferably less than
0.1 phr. In one embodiment, aromatic oil is present at 0 phr. Generally,
aromatic oils are compounds containing at least 35% by mass of single-
and multiple-ring components. Generally, aromatic oils contain
unsaturated polycyclic components. Some aromatic oils have about 35-55%
of the carbons in paraffinic chain-like structures (i.e., isoparaffinic
and normal paraffinic), 10-35% of the carbons in naphthenic structures
(i.e., saturated rings), and 30-40% of the carbons in aromatic structures
(i.e., unsaturated rings).

[0030]In yet another embodiment, the elastomeric composition is
substantially free of paraffinic oil. Substantially free of paraffinic
oil is defined to mean that paraffinic oil has not deliberately been
added to the elastomeric composition, or, in the alternative, if present
the elastomeric composition comprises less than 2 phr of paraffinic oil,
or less than 0.5 phr, or more preferably less than 0.25 phr, or most
preferably less than 0.1 phr. In one embodiment, paraffinic oil is
present at 0 phr. Generally, paraffinic oils have greater than 60% of the
carbons in paraffinic chain-like structures (i.e., isoparaffinic and
normal paraffinic), and less than 40% of the carbons in naphthenic
structures (i.e., saturated rings), and less than 20% of the carbons in
aromatic structures (i.e., unsaturated rings). Some paraffinic oils have
about 60-80% of the carbons in paraffinic chain-like structures, 20-40%
of the carbons in naphthenic structures, and 0-10% of the carbons in
aromatic structures.

[0031]In a further embodiment, the elastomeric composition is
substantially free of polybutene processing oil. Substantially free of
polybutene processing oil is defined to mean that polybutene processing
oil has not deliberately been added to the elastomeric composition, or,
in the alternative, if present the elastomeric composition comprises less
than 2 phr of polybutene processing oil, or less than 0.5 phr, or more
preferably less than 0.25 phr, or most preferably less than 0.1 phr. A
polybutene processing oil comprises 50 mole % or more of butene polymers,
and is a copolymer of at least isobutylene derived units, 1-butene
derived units, and 2-butene derived units. The polybutene processing oil
is preferably low molecular weight and has a number average molecular
weight of 15,000 g/mol or less.

Elastomer

[0032]The elastomeric compositions described herein comprise at least one
isobutylene-based elastomer. Typical isobutylene-based elastomers that
may be included in the compositions are C4 monoolefin based rubbers,
such as butyl rubber (isoprene-isobutylene rubber, "IIR"), branched
("star-branched") butyl rubber, star-branched polyisobutylene rubber,
bromobutyl ("BIIR"), chlorobutyl ("CIIR"), random copolymers of
isobutylene and para-methylstyrene
(poly(isobutylene-co-p-methylstyrene)), halogenated
poly(isobutylene-co-p-methylstyrene) ("BIMSM"), any halogenated versions
of these elastomers, and mixtures thereof. Useful elastomers can be made
by any suitable means known in the art, and the invention is not herein
limited by the method of producing the elastomer.

[0033]In some embodiments, the elastomeric composition comprises a blend
of two or more elastomers. Blends of elastomers may be reactor blends
and/or melt mixes. The individual elastomer components may be present in
various conventional amounts, with the total elastomer content in the
elastomeric composition being expressed in the formulation as 100 phr.

[0034]Useful elastomers include isobutylene-based homopolymers or
copolymers. An isobutylene based elastomer refers to an elastomer or
polymer comprising at least 70 mol % repeat units from isobutylene. These
polymers can be described as random copolymers of a C4 isomonoolefin
derived unit, such as an isobutylene derived unit, and at least one other
polymerizable unit. The isobutylene-based elastomer may or may not be
halogenated.

[0035]The elastomer may also be a butyl-type rubber or branched butyl-type
rubber, including halogenated versions of these elastomers. Useful
elastomers are unsaturated butyl rubbers such as homopolymers and
copolymers of olefins, isoolefins, and multiolefins. Non-limiting
examples of other useful unsaturated elastomers are
poly(isobutylene-co-isoprene), polyisobutylene, star-branched butyl
rubber, halogenated and non-halogenated random copolymers of isobutylene
and para-methylstyrene, and mixtures thereof.

[0036]The elastomer may or may not be halogenated. Preferred halogenated
elastomers may be selected from the group consisting of halogenated butyl
rubber, bromobutyl rubber, chlorobutyl rubber, halogenated branched
("star-branched") butyl rubbers, and halogenated random copolymers of
isobutylene and para-methylstyrene. Halogenation can be carried out by
any means, and the invention is not herein limited by the halogenation
process.

[0037]Examples of suitable commercially available halogenated butyl
rubbers include Bromobutyl 2222 and Bromobutyl 2225, both available from
ExxonMobil Chemical Company. Bromobutyl 2222 has a Mooney viscosity from
27 to 37 (ML 1+8 at 125° C., ASTM D1646), and the bromine content
is from 1.8 to 2.2 wt %. Further, cure characteristics of Bromobutyl 2222
are as follows: MH is from 28 to 40 dNm, ML is from 7 to 18 dNm (ASTM
D2084).

[0038]In one embodiment, the elastomer may be a branched or
"star-branched" butyl rubber ("SBB`). SBB is typically a composition of a
butyl rubber, either halogenated or not, and a polydiene or block
copolymer, either halogenated or not. In one embodiment, the SBB or
halogenated-SBB is a composition of a butyl or halogenated butyl rubber
and a copolymer of a polydiene and a partially hydrogenated polydiene
selected from the group including styrene, polybutadiene, polyisoprene,
polypiperylene, natural rubber, styrene-butadiene rubber,
ethylene-propylene diene rubber (EPDM), ethylene-propylene rubber (EPR),
styrene-butadiene-styrene, and styrene-isoprene-styrene block copolymers.
These polydienes are present in one embodiment, based on the monomer wt
%, greater than 0.3 wt %, or in another embodiment in the range of 0.3 to
3 wt %, or in the range of 0.4 to 2.7 wt %.

[0039]In one embodiment, the elastomer may be a random copolymer
comprising a C4 isomonoolefin, such as isobutylene, and an
alkystyrene comonomer, such as para-methylstyrene, containing at least
80%, alternatively at least 90%, by weight of the para-isomer.

[0040]The copolymers may optionally include functionalized interpolymers
wherein at least one or more of the alkyl substituent groups present in
the styrene monomer units contain a halogen or some other functional
group. In one embodiment, up to 60 mol % of the para-substituted styrene
present in the random polymer structure may be functionalized. In another
embodiment, the amount of functionalized para-methylstyrene is in the
range of 0.1 to 5 mol %, or in the range of 0.2 to 3 mol %. The
functional group may be halogen or some other functional group which may
be incorporated by nucleophilic substitution of benzylic halogen with
other groups such as carboxylic acids, carboxy salts, carboxy esters,
amides and imides, hydroxyl, alkoxide, phenoxide, thiolate, thioether,
xanthate, cyanide, cyanate, amino, and mixtures thereof. These
functionalized isomonoolefin copolymers, their method of preparation,
methods of functionalization, and cure are more particularly disclosed in
U.S. Pat. No. 5,162,445, incorporated herein by reference.

[0041]In a further embodiment, the elastomer comprises random copolymers
of isobutylene and para-methylstyrene containing from 0.5 to 20 mol %
para-methylstyrene wherein up to 60 mol % of the methyl substituent
groups present on the benzyl ring contain a bromine or chlorine atom, as
well as acid or ester functionalized versions thereof. In certain
embodiments, the random copolymers have a substantially homogeneous
compositional distribution such that at least 95% by weight of the
polymer has para-alkylstyrene content within 10% of the average
para-alkylstyrene content of the polymer. Exemplary polymers are
characterized by a narrow molecular weight distribution (Mw/Mn) of less
than 5, alternatively less than 2.5, an exemplary viscosity average
molecular weight in the range of 200,000 up to 2,000,000 and an exemplary
number average molecular weight in the range of 25,000 to 750,000 as
determined by gel permeation chromatography.

[0042]The elastomer may be a brominated
poly(isobutylene-co-p-methylstyrene) ("BIMSM"). BIMSM polymers generally
contain from 0.1 to 5% mole of bromomethylstyrene groups relative to the
total amount of monomer derived units in the copolymer. In one
embodiment, the amount of bromomethyl groups is in the range of 0.2 to
3.0 mol %, or in the range of 0.3 to 2.8 mol %, or in the range of 0.4 to
2.5 mol %, or in the range of 0.3 to 2.0 mol %, wherein a desirable range
may be any combination of any upper limit with any lower limit. Expressed
another way, exemplary copolymers may contain 0.2 to 10 wt % of bromine,
based on the weight of the polymer, or 0.4 to 6 wt % bromine, or 0.6 to
5.6 wt %, in another embodiment they are substantially free of ring
halogen or halogen in the polymer backbone chain. In one embodiment, the
random polymer is a copolymer of C4 to C7 isoolefin derived
units (or isomonoolefin), para-methylstyrene derived units, and
para-(halomethylstyrene) derived units, wherein the
para-(halomethylstyrene) units are present in the polymer in the range of
0.4 to 3.0 mol % based on the total number of para-methylstyrene, and
wherein the para-methylstyrene derived units are present in the range of
3 to 15 wt %, or in the range of 4 to 10 wt %, based on the total weight
of the polymer. In a preferred embodiment, the para-(halomethylstyrene)
is para-(bromomethylstyrene).

[0043]Commercial embodiments of useful halogenated
isobutylene-p-methylstyrene rubbers include EXXPRO® elastomers,
available from ExxonMobil Chemical Company, Houston, Tex., having a
Mooney viscosity (ML 1+8 at 125° C., ASTM D1646) in the range of
30 to 50, a p-methylstyrene content in the range of 4 to 8.5 wt %, and a
bromine content in the range of 0.7 to 2.2 wt % relative to the
halogenated isobutylene-p-methylstyrene rubber.

[0045]In another embodiment, the isobutylene-based elastomer in the
composition may be a blend of two or more different isobutylene-based
elastomers, alternately three or more, alternately four or more. By
"different isobutylene based elastomer" is meant the isobutylene based
elastomers differ in at least one of the following: a) comonomer type
(e.g. isoprene vs. para-alkylstyrene); b) molecular weight (Mn as
determined by GPC) by at least 10%; c) Mooney Viscosity (ML 1+8 at
125° C., ASTM D1646) by at least 10%; d) in comonomer content (by
at least 10%; as determined by C13 nuclear magnetic resonance or
infrared spectroscopy); e) in halogen content by at least 1%; and/or f)
in halogen type (e.g. Cl vs. Br). Alternately the b) and/or c) and/or d)
differ by at least 20%, alternately by at least 30%. In another
embodiment the halogen content varies by at least 2%, alternately by at
least 3% alternately by at least 5%.

[0046]In other embodiments, the isobutylene based elastomer portion of the
elastomeric composition comprises from 50 to 90 phr, or from 70 to 90
phr, of a first isobutylene-based elastomer and from 10 to 50 phr, or
from 15 to 30 phr, of different isobutylene based elastomer(s).

Secondary Elastomer

[0047]The elastomeric composition may further include a secondary
elastomer. A secondary elastomer may be used in combination with the at
least one isobutylene-based elastomer to provide a balance of properties.
For example, the elastomeric composition may comprise differing amounts
of at least one isobutylene-based elastomer and a secondary elastomer to
provide beneficial compound Mooney viscosity, Mooney scorch, curing
characteristics, air impermeability, flex fatigue retention, and adhesion
to adjacent components in a cured tire.

[0048]The secondary elastomer is generally a non isobutylene based rubber
of types conventionally used in tire rubber compounding, herein referred
to as "general purpose rubbers." A general purpose rubber may be any
rubber that usually provides high strength and good abrasion along with
low hysteresis and high resilience.

[0050]In one embodiment, the secondary elastomer is a general purpose
rubber such as polybutadiene rubber ("BR"). Another useful general
purpose rubber is high cis-polybutadiene ("cis-BR"). By
"cis-polybutadiene" or "high cis-polybutadiene", it is meant that 1,4-cis
polybutadiene is used, wherein the amount of cis component is at least
95%.

[0051]In yet another embodiment, the secondary elastomer may comprise
rubbers of ethylene and propylene derived units such as EP and EPDM.
Examples of suitable comonomers in making EPDM are ethylidene norbornene,
1,4-hexadiene, dicyclopentadiene, as well as others. In one embodiment,
the secondary elastomer may comprise an ethylene/alpha-olefin/diene
terpolymer. The alpha-olefin may be selected from the group consisting of
C3 to C20 alpha-olefin with propylene, butene and octene being
preferred and propylene most preferred. The diene component may be
selected from the group consisting of C4 to C20 dienes.

[0052]In a preferred embodiment, the secondary elastomer is a natural
rubber. Desirable natural rubbers may be selected from technically
specified rubbers ("TSR"), such as Malaysian rubbers which include, but
are not limited to, SMR CV, SMR 5, SMR 10, SMR 20, SMR 50, and mixtures
thereof. Preferred natural rubbers have a Mooney viscosity at 100°
C. (ML 1+4, ASTM D1646) in the range of 30 to 120, or in the range of 40
to 80.

[0053]In one embodiment, the elastomeric composition comprises 100 phr of
an isobutylene-based elastomer. In another embodiment, the elastomeric
composition comprises a blend of at least one isobutylene-based elastomer
and a secondary elastomer which is a non-isobutylene based elastomer.

[0054]In some embodiments, the elastomeric composition comprises from 50
to 100 phr, or from 70 to 100 phr, or from 75 to 95 phr, of
isobutylene-based elastomers, and less than or equal to 50 phr, or less
than or equal to 30 phr, or less than or equal to 15 phr, or less than or
equal to 10 phr of a secondary elastomer. In one embodiment, the
elastomeric composition comprises from 90 to 100 phr of isobutylene based
elastomers and less than or equal to 10 phr of a secondary elastomer. The
secondary elastomer may be natural rubber.

[0055]In one embodiment, a secondary elastomer other than natural rubber
is present; however no natural rubber is added to the elastomeric
composition. In some embodiments the elastomeric composition comprises 0
phr of natural rubber.

[0056]In other embodiments, the elastomeric composition comprises from 50
to 90 phr or from 70 to 90 phr of isobutylene-based elastomers and from
10 to 50 phr or from 15 to 30 phr of a secondary elastomer. The secondary
elastomer may be natural rubber.

[0057]The elastomers and/or secondary elastomers may be blended with
various other rubbers or plastics, in particular thermoplastic resins
such as nylons or polyolefins such as polypropylene or copolymers of
polypropylene. These compositions are useful in air barriers such as
bladders, tire innertubes, tire innerliners, air sleeves (such as in air
shocks), diaphragms, as well as other applications where high air or
oxygen retention is desirable.

Hydrocarbon Fluid Additive

[0058]The elastomeric compositions described herein include at least one
hydrocarbon fluid additive ("HFA"). The classes of materials described
herein that are useful as HFAs can be utilized alone or admixed with
other HFAs described herein to obtain desired properties. Any HFA useful
in the present invention may also be described by any number of, or any
combination of, parameters described herein.

[0059]In one embodiment, the HFA is defined to be a hydrocarbon liquid
compound comprising carbon and hydrogen, having functional groups
selected from hydroxide, aryls, substituted aryls, halogens, alkoxys,
carboxylates, esters, carbon unsaturation, acrylates, oxygen, nitrogen,
and carboxyl present to an unappreciable extent. By "unappreciable
extent", it is meant that these groups and compounds comprising these
groups are not deliberately added to the HFA, and if present at all for
any reason, are present at less than 5 wt %, or less than 3 wt %, or
preferably less than 1 wt %, or less than 0.5 wt %, or less than 0.1 wt
%, or less than 0.05 wt %, or less than 0.01 wt %, or less than 0.001 wt
%, based upon the weight of the HFA.

[0060]In some embodiment, aromatic moieties (including compounds whose
molecules have the ring structure characteristic of benzene, naphthalene,
phenanthrene, anthracene, etc.) are substantially absent from the HFA. In
yet another embodiment, naphthenic moieties (including compounds whose
molecules have a saturated ring structure such as would be produced by
hydrogenating benzene, naphthalene, phenanthrene, anthracene, etc.) are
substantially absent from the HFA. By "substantially absent", it is meant
that the aromatic moieties or the naphthenic moieties are not
deliberately added to the HFA, and if present at all for any reason, are
present at less than 5 wt %. Preferably, these groups and compounds are
present at less than 4 wt %, or less than 3 wt %, or less than 2 wt %, or
less than 1 wt %, or less than 0.7 wt %, or less than 0.5 wt %, or less
than 0.3 wt %, or less than 0.1 wt %, or less than 0.05 wt %, or less
than 0.01 wt %, or less than 0.001 wt %, based upon the weight of the
HFA.

[0061]In some embodiments, the HFA is a hydrocarbon that contains olefinic
unsaturation to an unappreciable extent. By "unappreciable extent of
olefinic unsaturation", it is meant that the carbons involved in olefinic
bonds account for less than 10%, or less than 6%, or less than 2%, or
preferably less than 1%, or less than 0.5%, or less than 0.1%, or less
than 0.05%, or less than 0.01%, or less than 0.001%, of the total number
of carbons. In some embodiments, the percent of carbons of the HFA
involved in olefinic bonds is in the range of 0.001 to 10%, or in the
range of 0.01 to 5%, or in the range of 0.1 to 2%, of the total number of
carbon atoms in the HFA.

[0062]Particularly preferred HFAs include a) polyalphaolefins, b) high
purity hydrocarbon fluids derived from a so-called Gas-To-Liquids
processes, and c) Group III Mineral Oils; with a viscosity index greater
than 100 (preferably greater than 120), a pour point less than
-15° C. (preferably less than -20° C.), a specific gravity
less than 0.88 (preferably less than 0.86), and a flash point greater
than 200° C. (preferably greater than 230° C.).

[0064]In preferred embodiments, the HFA has a pour point of -10° C.
or less, preferably -20° C. or less, preferably -30° C. or
less, preferably -40° C. or less, preferably -45° C. or
less, preferably -50° C. or less, preferably -10 to -100°
C., preferably -15 to -80° C., preferably -15 to -75° C.,
preferably -20 to -70° C., preferably -25 to -65° C.,
preferably greater than -120° C., wherein a desirable range may be
any combination of any lower pour point limit with any upper pour point
limit described herein.

[0065]In another embodiment, the HFA has a pour point of less than
-30° C. when the kinematic viscosity at 40° C. is from 20
to 600 cSt (preferably 30 to 400 cSt, preferably 40 to 300 cSt). Most
mineral oils, which typically include aromatic moieties and other
functional groups, have a pour point of from 10 to -20° C. in the
same kinematic viscosity range.

[0066]In a preferred embodiment, the HFA has a glass transition
temperature (Tg) of -40° C. or less, preferably -50°
C. or less, preferably -60° C. or less, preferably -70° C.
or less, preferably -80° C. or less, preferably -45 to
-120° C., preferably -65 to -90° C., wherein a desirable
range may be any combination of any lower Tg limit with any upper
Tg limit described herein.

[0067]In preferred embodiments, the HFA has a Viscosity Index (VI) of 100
or more, preferably 110 or more, preferably 120 or more, preferably 130
or more, preferably 115 to 350, preferably 135 to 300, preferably 140 to
250, preferably 150 to 200, preferably 125 to 180, wherein a desirable
range may be any combination of any lower VI limit with any upper VI
limit described herein.

[0068]In preferred embodiments, the HFA has a flash point of 200°
C. or greater, preferably 210° or greater, preferably 230°
C. or greater, preferably 200 to 320° C., preferably 210 to
300° C., preferably 215 to 290° C., preferably 220 to
280° C., preferably 240 to 280° C., wherein a desirable
range may be any combination of any lower flash point limit with any
upper flash point limit described herein.

[0069]In preferred embodiments, the HFA has a specific gravity of 0.88 or
less, or 0.86 or less, preferably 0.855 or less, preferably 0.84 or less,
preferably 0.78 to 0.86, preferably 0.79 to 0.855, preferably 0.80 to
0.85, preferably 0.81 to 0.845, preferably 0.82 to 0.84, wherein a
desirable range may be any combination of any lower specific gravity
limit with any upper specific gravity limit described herein.

[0070]In preferred embodiments, the HFA has a low degree of color, such as
typically identified as "water white", "prime white", "standard white",
or "bright and clear," preferably an APHA color of 100 or less
(preferably 80 or less, preferably 60 or less, preferably 40 or less,
preferably 20 or less).

[0071]In other embodiments, any HFA may have an initial boiling point of
from 300 to 600° C. (preferably 350 to 500° C., preferably
greater than 400° C.).

[0072]Any of the HFAs for use in the present invention may be described by
any embodiment described herein or any combination of the embodiments
described herein.

[0073]In some embodiments, the HFA described herein has a flash point of
200° C. or more (preferably 210° C. or more, or 220°
C. or more, or 230° C. or more) and a pour point of -15° C.
or less (or -20° C. or less, or preferably -25° C. or less,
preferably -30° C. or less, preferably -35° C. or less,
preferably -45° C. or less, preferably -50° C. or less).

[0074]In certain embodiments, the HFA has a) a specific gravity of 0.86 or
less (preferably 0.855 or less, preferably 0.85 or less); b) a VI of 120
or more (preferably 135 or more, preferably 140 or more); and c) a flash
point of 200° C. or more (preferably 220° C. or more,
preferably 240° C. or more).

[0075]In certain embodiments, the HFA has a) a flash point of 200°
C. or more; b) a specific gravity of 0.88, or 0.86 or less; c) a pour
point of -15° C. or less; and d) a viscosity index of 120 or more.

[0076]In another embodiment, the HFA has a pour point of -20° C. or
less, preferably -30° C. or less, and one or more of the following
properties: [0077]i. a kinematic viscosity at 100° C. of 3 cSt
or greater (preferably 6 cSt or greater, preferably 8 cSt or greater,
preferably 10 cSt or more); and/or, [0078]ii. a Viscosity Index of 120 or
greater (preferably 130 or greater); and/or, [0079]iii. a low degree of
color, such as typically identified as "water white", "prime white",
"standard white", or "bright and clear," preferably APHA color of 100 or
less (preferably 80 or less, preferably 60 or less, preferably 40 or
less, preferably 20 or less, preferably 15 or less); and/or [0080]iv. a
flash point of 200° C. or more (preferably 220° C. or more,
preferably 240° C. or more); and/or [0081]v. a specific gravity
(15.6° C.) of less than 0.86.

[0082]Most mineral oils have a kinematic viscosity at 100° C. of
less than 6 cSt, or an APHA color of greater than 20, or a flash point
less than 200° C. when their pour point is less than -20°
C.

[0083]In certain embodiments, the HFA has a pour point of -15° C.
or less (preferably -15° C. or less, preferably -20° C. or
less, preferably -25° C. or less), a VI of 120 or more (preferably
135 or more, preferably 140 or more), and optionally a flash point of
200° C. or more (preferably 220° C. or more, preferably
240° C. or more).

[0084]In certain embodiments, the HFA has a pour point of -20° C.
or less (preferably -25° C. or less, preferably -30° C. or
less, preferably -40° C. or less) and one or more of the
following: [0085]i. a flash point of 200° C. or more (preferably
220° C. or more, preferably 240° C. or more), and/or
[0086]ii. a VI of 120 or more (preferably 135 or more, preferably 140 or
more), and/or [0087]iii. a KV100 of 4 cSt or more (preferably 6 cSt or
more, preferably 8 cSt or more, preferably 10 cSt or more), and/or
[0088]iv. a specific gravity of 0.86 or less (preferably 0.855 or less,
preferably 0.85 or less).

[0089]In certain embodiments, the HFA has a KV100 of 4 cSt or more
(preferably 5 cSt or more, preferably 6 cSt or more, preferably 8 cSt or
more, preferably 10 cSt or more), a specific gravity of 0.86 or less
(preferably 0.855 or less, preferably 0.85 or less), and a flash point of
200° C. or more (preferably 220° C. or more, preferably
240° C. or more).

[0090]In a embodiment, the HFA has a flash point of 200° C. or more
(preferably 220° C. or more, preferably 240° C. or more), a
pour point of -10° C. or less (preferably -15° C. or less,
preferably -20° C. or less, preferably -25° C. or less), a
specific gravity of 0.86 or less (preferably 0.855 or less, preferably
0.85 or less), a KV100 of 4 cSt or more (preferably 5 cSt or more,
preferably 6 cSt or more, preferably 8 cSt or more, preferably 10 cSt or
more), and optionally a VI of 100 or more (preferably 120 or more,
preferably 135 or more).

[0091]In a embodiment, the HFA has a flash point of 200° C. or more
(preferably 210° C. or more, preferably 220° C. or more), a
pour point of -10° C. or less (preferably -20° C. or less,
preferably -30° C. or less), and a KV100 of 6 cSt or more
(preferably 8 cSt or more, preferably 10 cSt or more, preferably 15 cSt
or more).

[0092]In certain embodiments, the HFA has a pour point of -20° C.
or less (preferably -25° C. or less, preferably -30° C. or
less, preferably -40° C. or less) and one or more of the
following: [0093]i. a flash point of 200° C. or more (preferably
220° C. or more, preferably 240° C. or more), and/or
[0094]ii. a VI of 120 or more (preferably 135 or more, preferably 140 or
more), and/or [0095]iii. a KV100 of 4 cSt or more (preferably 6 cSt or
more, preferably 8 cSt or more, preferably 10 cSt or more), and/or
[0096]iv. a specific gravity of 0.86 or less (preferably 0.855 or less,
preferably 0.85 or less).

[0097]In a embodiment, the HFA has a KV100 of 35 cSt or more (preferably
40 or more) and a specific gravity of 0.86 or less (preferably 0.855 or
less), and optionally one or more of the following: [0098]a) a flash
point of 200° C. or more (preferably 220° C. or more,
preferably 240° C. or more), and/or [0099]b) a pour point of
-10° C. or less (preferably -15° C. or less, preferably
-20° C. or less, preferably -25° C. or less).

[0100]In a preferred embodiment, the percentage of carbons in chain-type
paraffins (CP) for any HFA is at least 80% (preferably at least 85%,
preferably at least 90%, even preferably at least 95%, even preferably at
least 98%, most preferably at least 99%). Chain-type paraffins (CP)
are determined as described in US 2008/0045638.

Polyalphaolefin

[0101]In preferred embodiments, the HFA is a polyalphaolefin ("PAO"). In
general, PAOs are oligomers of α-olefins (also known as 1-olefins)
having a VI of 120 or more and are often used as the base stock for
synthetic lubricants. PAOs are typically produced by the polymerization
of alpha-olefins typically ranging from 1-octene to 1-dodecene, with
1-decene being a preferred material, although polymers of lower olefins
such as ethylene and propylene may also be used, including copolymers of
ethylene with higher olefins. The various grades of PAOs are mainly
distinguished by their molecular weight or by their kinematic viscosity
measured in centistokes (cSt) at 100° C. PAOs are Group 4
compounds, as defined by the American Petroleum Institute (API). Useful
PAOs are described in, for example, U.S. Pat. No. 3,149,178; U.S. Pat.
No. 4,827,064; U.S. Pat. No. 4,827,073; U.S. Pat. No. 5,171,908; and U.S.
Pat. No. 5,783,531 and in SYNTHETIC LUBRICANTS AND HIGH-PERFORMANCE
FUNCTIONAL FLUIDS, Leslie R. Rudnick & Ronald L. Shubkin, eds. (Marcel
Dekker, 1999), p. 3-62.

[0102]A PAO is not a polymer. (A polymer is defined to be 75 mer units or
more).

[0103]Useful PAOs may be made by any suitable means known in the art, and
the invention is not herein limited by the method of producing the PAO.
In one embodiment, the PAOs may be produced by the oligomerization or
polymerization of alpha-olefins in the presence of a Friedel-Crafts
(Lewis acid) catalyst, such as, for example, AlCl3, BF3, or a
coordination complex such as ethylaluminum sesquichloride+TiCl4.
Alternatively, the PAO may be produced using a single-site coordination
catalyst, such as a metallocene catalyst or a constrained geometry
catalyst.

[0104]Subsequent to the polymerization, the PAO may be hydrogenated in
order to reduce any residual unsaturation. Preferred PAOs are
hydrogenated to yield substantially (>99 wt %) paraffinic materials.
The PAOs may also be functionalized to comprise, for example, esters,
polyethers, polyalkylene glycols, and the like.

[0106]In one embodiment, the PAO comprises oligomers of a single
alpha-olefin species having a carbon number of 5 to 24 (preferably 6 to
18, preferably 8 to 12, most preferably 10). In another embodiment, the
PAO comprises oligomers of mixed alpha-olefins (i.e., involving two or
more alpha-olefin species), each alpha-olefin having a carbon number of 3
to 24 (preferably 5 to 24, preferably 6 to 18, most preferably 8 to 12,
or 8 to 14, or 8 to 16), provided that alpha-olefins having a carbon
number of 3 or 4 are present at 10 wt % or less. In a preferred
embodiment, the PAO comprises oligomers of mixed alpha-olefins (i.e.,
involving two or more alpha-olefin species) where the weighted average
carbon number for the alpha-olefin mixture is 6 to 14 (preferably 8 to
12, preferably 9 to 11).

[0107]In one embodiment, at least one of the alpha-olefins is a linear
alpha-olefin (LAO); more preferably, all the alpha-olefins are LAOs.
Preferred PAO's comprise linear alpha olefins having 5 to 18 carbon
atoms, preferably 6 to 12 carbon atoms, more preferably 8 to 12 carbon
atoms, still more preferably an average of about 10 carbon atoms.
Suitable LAOs include ethylene, propylene, 1-butene, 1-pentene, 1-hexene,
1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene,
1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, and blends
thereof. Preferably, C2, C3, and C4 alpha-olefins (i.e.,
ethylene, propylene and 1-butene and/or isobutylene) are present in the
PAO oligomers at an average concentration of 30 wt % or less, or 20 wt %
or less, or 10 wt % or less, or 5 wt % or less; more preferably, C2,
C3, and C4 alpha-olefins are not present in the PAO oligomers.

[0108]In one or more embodiments, the PAO comprises oligomers of two or
more C2 to C24, or C3 to C20 LAOs, to make
`bipolymer` or `terpolymer` or higher-order copolymer combinations. Other
embodiments involve oligomerization of a mixture of LAOs selected from
C6 to C18 LAOs with even carbon numbers, preferably a mixture
of two or three LAOs selected from 1-hexene, 1-octene, 1-decene,
1-dodecene, 1-tetradecene, and 1-hexadecene.

[0109]In general, PAOs are high purity hydrocarbons with a fully
paraffinic structure and a high-degree of side-chain branching. The PAO
may have irregular branching or regular branching. The PAO may comprise
oligomers or low molecular weight polymers of branched and/or linear
alpha olefins. Preferred PAOs have a "branching ratio," as defined in
U.S. Pat. No. 4,827,064 and measured according to the method described
therein, of 0.20 or less, or 0.18 or less, or 0.15 or less, or 0.10 or
less.

[0110]The PAO may be a blend or mixture of one or more distinct PAOs with
different compositions and/or different physical properties (e.g.,
kinematic viscosity, pour point, and/or viscosity index).

[0111]The PAO or blend of PAOs may have a kinematic viscosity ("KV") at
100° C. (as measured by ASTM D445 at 100° C.) (1 cSt=1
mm2/s) of 3 cSt or more, or 4 cSt or more, or 5 cSt or more, or 6
cSt or more, or 8 cSt or more, or 10 cSt or more, or 20 cSt or more, or
30 cSt or more, or 40 cSt or more, or 80 cSt or more, or 100 cSt or more,
or 150 cSt or more, or 200 cSt or more, or 300 cSt or more, or 500 cSt or
more, or 750 or more, or 1000 cSt or more. In some embodiments, the PAO
has a KV at 100° C. in the range of 3 to 3,000 cSt, or 4 to 1,000
cSt, preferably 4 to 300 cSt, or 5 to 150 cSt, or 6 to 100 cSt, or 6 to
40 cSt. In other embodiments, the PAO or blend of PAOs has a
KV100° C. in the range of 3 cSt to 20 cSt, or in the range of 5
cSt to 15 cSt, or preferably in the range of 6 cSt to 10 cSt. In further
embodiments, the PAO or blend of PAOs has a KV100° C. in the range
of 40 to 200 cSt, or in the range of 60 to 150 cSt, or preferably 80 cSt
to 120 cSt.

[0112]The PAO or blend of PAO may have a viscosity index ("VI"), as
determined by ASTM D-2270, of 100 or more, or 110 or more, or 120 or
more, or 130 or more, or 140 or more, or 150 or more, or 170 or more, or
200 or more, or 250 or more, or 300 or more. Preferred PAOs have a VI in
the range of 90 to 400, or in the range of 100 to 350, or 120 to 250, or
130 to 180, or in other embodiments in the range of 110 to 150 or 120 to
140.

[0113]PAOs with KV at 100° C. of 10 cSt or less generally have a VI
of less than 150. A PAO with a high VI can be advantageous as a higher VI
may indicate that the PAO has a higher viscosity at higher temperatures
where polymer processing takes place such as, 200° C. or more;
therefore, blending the PAO into the polymer may be facilitated (it is
well known that homogeneous mixing of materials with severely mismatched
viscosities such as a high viscosity polymer and a low viscosity fluid is
difficult). On the other hand, for a given viscosity at high temperature
(e.g., 200° C.), a higher VI means the PAO has a lower viscosity
at room temperature, so the PAO is easier to pump. In certain
embodiments, the PAO or blend of PAOs has a KV100° C. of 10 cSt or
less and a VI of 150 or more. In other embodiments, the PAO or blend of
PAOs has a KV100° C. of 150 cSt or less, preferably between 10 and
150 cSt, and a VI of greater than 105(KV100° C.)0.13 where
KV100° C. is measured in cSt.

[0114]Useful PAOs typically possess a number average molecular weight (Mn)
in the range of 100 to 21,000 g/mole, or 300 to 15,000, or 200 to 10,000,
or 200 to 7,000, or 600 to 3,000, or in other embodiments in the range of
200 to 2,000 g/mole or 200 to 500 g/mole.

[0115]Useful PAOs have a weight average molecular weight (Mw) of less than
20,000 g/mole, or less than 10,000 g/mole, or less than 5,000 g/mole, or
more preferably less than 4,000 g/mole, or less than 2,000 g/mole, or
less than 500 g/mole. In some embodiments, the PAO may have an Mw of 1000
g/mole or more, or 2000 g/mole or more, or 2500 g/mole or more, or 3000
g/mole or more, or 3500 g/mole or more. In other embodiments the PAO may
have an Mw in the range of 100 to 20,000 g/mole, or 200 to 10,000 g/mole,
or 200 to 7,000 g/mole, or in the range of 2000 g/mole to 4000 g/mole, or
in the range of 2500 g/mole to 3500 g/mole.

[0116]In one or more embodiments, the PAO or blend of PAOs has a molecular
weight distribution as characterized by the ratio of the weight- and
number-averaged molecular weights (Mw/Mn) of 4 or less, or 3 or
less, or 2.5 or less, or 2.3 or less, or 2.1 or less, or 2.0 or less, or
1.9 or less, or 1.8 or less. In other embodiments, the PAO or blend of
PAOs has an Mw/Mn in the range of 1 to 2.5, preferably 1.1 to
2.3, or 1.1 to 2.1, or 1.1 to 1.9.

[0117]Preferably the PAO has a pour point, as determined by ASTM D97, of
less than -15° C. or less, more preferably -20° C. or less,
or -30° C. or less, or -40° C. or less, or -50° C.
or less; or in some embodiments in the range of -20 to -80° C., or
-30 to -70° C., or -15 to -70° C., or -25 to -60° C.

[0118]The PAO may have a dielectric constant, as measured by ASTM D 924,
at 20° C. of less than 3.0, or less than 2.8, or less than 2.5, or
less than 2.3, or less than 2.1.

[0119]Useful PAOs may have a specific gravity (ASTM D 4052, 15.6°
C.) of less than 0.880, or less than 0.86, or less than 0.855, or less
than 0.85, or more preferably in the range of 0.650 to 0.880, or 0.700 to
0.860, or 0.750 to 0.855, or 0.790 to 0.850, or 0.800 to 0.840.

[0120]Particularly preferred PAO's for use herein are those having a flash
point as measured by the open cup method (ASTM-D92) of 200° C. or
more, or 220° C. or more, or 230° C. or more, or
250° C. or more. In some embodiments, the PAO may have a flash
point in the range of about 200 to 300° C., or in the range of
about 210 to 275° C., or in the range of about 220 to 250°
C.

[0121]In one or more embodiments, the PAO or blend of PAOs has a glass
transition temperature (Tg) of -40° C. or less, or
-50° C. or less, or -60° C. or less, or -70° C. or
less, or -80° C. or less, preferably in the range of -50 to
-120° C., or in some embodiments in the range of 60 to
-100° C. or -70 to -90° C.

[0122]Useful PAOs or blends of PAOs may have one or more of the above
described properties. For example, in one embodiment, the PAO comprises
C6 to C14 olefins having a kinematic viscosity of 10 cSt or
more at 100° C., and a viscosity index of 120 or more, or 130 or
more.

[0123]In another embodiment, a useful PAO is one having a flash point of
200° C. or more (preferably 220° C. or more, or 230°
C. or more, or 250° C. or more) and a pour point less than
-25° C. (preferably less than -30° C., or less than
-35° C., or less than -40° C.).

[0124]In a further embodiment, an advantageous PAO or blend of PAOs are
those having i) a flash point of 200° C. or more, preferably
210° C. or more, or 220° C. or more, or 230° C. or
more; ii) a pour point less than -20° C., preferably less than
-25° C., or less than -30° C., or less than -35° C.,
or less than -40° C.; and iii) a KV100° C. of 10 cSt or
more, preferably 35 cSt or more, or 40 cSt or more, or 60 cSt or more.

[0125]In yet another embodiment, the PAO or blends of PAOs have i) a
KV100° C. of at least 3 cSt, preferably at least 4 cSt, or at
least 6 cSt, or at least 8 cSt, or at least 10 cSt; ii) a VI of at least
120, preferably at least 130, or at least 140, or at least 150; iii) a
pour point of -15° C. or less, preferably -20° C. or less,
or -30° C. or less, or -40° C. or less; and iv) a specific
gravity (15.6° C.) of 0.86 or less preferably 0.855 or less, or
0.85 or less, or 0.84 or less.

[0126]Advantageous blends of PAOs include blends of two or more PAOs where
the ratio of the highest KV100° C. to the lowest KV100° C.
is at least 1.5, preferably at least 2, or at least 3, or at least 5.
Other blends of PAO also include two or more PAOs where at least one PAO
has a KV100° C. of 300 cSt or more and at least one other PAO has
a KV100° C. of less than 300 cSt; or a blend where at least one
PAO has a KV100° C. of 150 cSt or more and at least one other PAO
has a KV100° C. of less than 150 cSt; or a blend where at least
one PAO has a KV100° C. of 100 cSt or more and at least one other
PAO has a KV100° C. of less than 100 cSt; or a blend where at
least one PAO has a KV100° C. of 40 cSt or more and at least one
PAO has a KV100° C. of less than 40 cSt; or at least one PAO has a
KV100° C. of 10 cSt or more and at least one PAO has a
KV100° C. of less than 10 cSt.

[0127]When a PAO or combination of more than one PAOs is employed, it is
preferred that the PAO or combination of PAOs have a pour point less than
or equal to -38° C. and/or a Kinematic viscosity less than or
equal to 10.5 cSt at 100° C. Such formulations may include a PAO
having one or more of the properties described herein and another PAO
with properties that may or may not have one or more of the properties
described herein as long as the combination of PAOs have a pour point
less than or equal to -38° C. and/or a Kinematic viscosity less
than or equal to 10.5 cSt at 100° C.

[0128]Desirable PAOs are available as SpectraSyn® and SpectraSyn
Ultra® from ExxonMobil Chemical in Houston, Tex. (previously sold
under the SHF and SuperSyn® tradenames by ExxonMobil Chemical
Company). Other useful PAOs include Synfluid® available from
ChevronPhillips Chemical Company (Pasadena, Tex.), Durasyn® available
from Innovene (Chicago, Ill.), Nexbase® available from Neste Oil
(Keilaniemi, Finland), and Synton® available from Chemtura Corporation
(Middlebury, Conn.). The percentage of carbons in chain-type paraffinic
structures (CP) is close to 100% (typically greater than 98% or even
99%) for PAOs.

[0129]In a preferred embodiment of the present invention, the PAO is not
an oligomer of C4 olefins (i.e., 1-butene, 2-butene, isobutylene,
butadiene, and mixtures thereof), including polybutenes and/or PIB and/or
PNB. In another embodiment, the PAO contains less than 90 wt %
(preferably less than 80 wt %, preferably less than 70 wt %, preferably
less than 60 wt %, preferably less than 50 wt %, preferably less than 40
wt %, preferably less than 30 wt %, preferably less than 20 wt %,
preferably less than 10 wt %, preferably less than 5 wt %, preferably
less than 2 wt %, preferably less than 1 wt %, preferably 0 wt %) of
C4 olefins, in particular 1-butene and isobutylene.

[0130]Preferably, the PAO is not a naphthenic mineral oil (also called a
naphthenic process oil or a naphthenic extender oil), nor is it an
aromatic mineral oil (also called an aromatic process oil or an aromatic
extender oil). More preferably, naphthenic and aromatic mineral oils are
substantially absent from the compositions of the present invention. In
certain embodiments, paraffinic mineral oils with a kinematic viscosity
at 40° C. of less than 80 cSt and a pour point of greater than
-15° C. are substantially absent from the compositions of the
present invention.

High Purity Hydrocarbon Fluids

[0131]In an alternate embodiment, the HFA may be high purity hydrocarbon
fluid as described at paragraph [0275] on page 16 to paragraph [0303] on
page 18 of US 2008/0045638. Preferably the high purity hydrocarbon fluid
has a flash point of 200° C. or more and a pour point of
-15° C. or less.

[0132]In one embodiment, the HFA is a high purity hydrocarbon fluid of
lubricating viscosity comprising a mixture of C20 to C120
paraffins, 50 wt % or more being isoparaffinic hydrocarbons and less than
50 wt % being hydrocarbons that contain naphthenic and/or aromatic
structures. Preferably, the mixture of paraffins comprises a wax
isomerate lubricant basestock or oil, which includes: [0133]i.
hydroisomerized natural and refined waxes, such as slack waxes, deoiled
waxes, normal alpha-olefin waxes, microcrystalline waxes, and waxy stocks
derived from gas oils, fuels hydrocracker bottoms, hydrocarbon
raffinates, hydrocracked hydrocarbons, lubricating oils, mineral oils,
polyalphaolefins, or other linear or branched hydrocarbon compounds with
carbon number of about 20 or more; and [0134]ii. hydroisomerized
synthetic waxes, such as Fischer-Tropsch waxes (i.e., the high boiling
point residues of Fischer-Tropsch synthesis, including waxy
hydrocarbons)or mixtures thereof. Most preferred are lubricant basestocks
or oils derived from hydrocarbons synthesized in a Fischer-Tropsch
process as part of an overall Gas-to-Liquids (GTL) process.

[0135]In one embodiment, the mixture of paraffins has two or more of the
following properties: [0136]1. a naphthenic content of less than 40 wt
% (preferably less than 30 wt %, preferably less than 20 wt %, preferably
less than 15 wt %, preferably less than 10 wt %, preferably less than 5
wt %, preferably less than 2 wt %, preferably less than 1 wt %) based on
the total weight of the hydrocarbon mixture; and/or [0137]2. a normal
paraffins content of less than 5 wt % (preferably less than 4 wt %,
preferably less than 3 wt %, preferably less than 1 wt %) based on the
total weight of the hydrocarbon mixture; and/or [0138]3. an aromatic
content of 1 wt % or less (preferably 0.5 wt % or less); and/or [0139]4.
a saturates level of 90 wt % or higher (preferably 95 wt % or higher,
preferably 98 wt % or higher, preferably 99 wt % or higher); and/or
[0140]5. the percentage of carbons in chain-type paraffinic structures
(CP) of 80% or more (preferably 90% or more, preferably 95% or more,
preferably 98% or more); and/or [0141]6. a branched paraffin:normal
paraffin ratio greater than about 10:1 (preferably greater than 20:1,
preferably greater than 50:1, preferably greater than 100:1, preferably
greater than 500:1, preferably greater than 1000:1); and/or [0142]7.
sidechains with 4 or more carbons making up less than 10% of all
sidechains (preferably less than 5%, preferably less than 1%); and/or
[0143]8. sidechains with 1 or 2 carbons making up at least 50% of all
sidechains (preferably at least 60%, preferably at least 70%, preferably
at least 80%, preferably at least 90%, preferably at least 95%,
preferably at least 98%); and/or [0144]9. a sulfur content of 300 ppm or
less (preferably 100 ppm or less, preferably 50 ppm or less, preferably
10 ppm or less) where ppm is on a weight basis; and/or [0145]10. a
nitrogen content of 300 ppm or less (preferably 100 ppm or less,
preferably 50 ppm or less, preferably 10 ppm or less) where ppm is on a
weight basis; and/or [0146]11. a number-average molecular weight of 300
to 1800 g/mol (preferably 400 to 1500 g/mol, preferably 500 to 1200
g/mol, preferably 600 to 900 g/mol); and/or [0147]12. a kinematic
viscosity at 40° C. of 10 cSt or more (preferably 25 cSt or more,
preferably between about 50 and 400 cSt); and/or [0148]13. a kinematic
viscosity at 100° C. ranging from 2 to 50 cSt (preferably 3 to 30
cSt, preferably 5 to 25 cSt, preferably 6 to 20 cSt, preferably 8 to 16
cSt); and/or [0149]14. a viscosity index (VI) of 80 or greater
(preferably 100 or greater, preferably 120 or greater, preferably 130 or
greater, preferably 140 or greater, preferably 150 or greater, preferably
160 or greater, preferably 180 or greater); and/or [0150]15. a pour point
of -5° C. or lower (preferably -10° C. or lower, preferably
-15° C. or lower, preferably -20° C. or lower, preferably
-25° C. or lower, preferably -30° C. or lower); and/or
[0151]16. a flash point of 200° C. or more (preferably 220°
C. or more, preferably 240° C. or more, preferably 260° C.
or more); and/or [0152]17. a specific gravity (15.6°
C./15.6° C.) of 0.86 or less (preferably 0.85 or less, preferably
0.84 or less); and/or [0153]18. an aniline point of 120° C. or
more; and/or [0154]19. a bromine number of 1 or less.

[0156]The synthesis of hydrocarbons, including waxy hydrocarbons, by F-T
may involve any suitable process known in the art, including those
involving a slurry, a fixed-bed, or a fluidized-bed of catalyst particles
in a hydrocarbon liquid. The catalyst may be an amorphous catalyst, for
example based on a Group VIII metal such as Fe, Ni, Co, Ru, and Re on a
suitable inorganic support material, or a crystalline catalyst, for
example a zeolitic catalyst. The process of making a lubricant basestock
or oil from a waxy stock is characterized as a hydrodewaxing process. A
hydrotreating step, while typically not required for F-T waxes, can be
performed prior to hydrodewaxing if desired. Some F-T waxes may benefit
from removal of oxygenates while others may benefit from oxygenates
treatment prior to hydrodewaxing. The hydrodewaxing process is typically
conducted over a catalyst or combination of catalysts at high
temperatures and pressures in the presence of hydrogen. The catalyst may
be an amorphous catalyst, for example based on Co, Mo, W, etc. on a
suitable oxide support material, or a crystalline catalyst, for example a
zeolitic catalyst such as ZSM-23 and ZSM-48 and others disclosed in U.S.
Pat. No. 4,906,350, often used in conjunction with a Group VIII metal
such as Pd or Pt. This process may be followed by a solvent and/or
catalytic dewaxing step to lower the pour point of the hydroisomerate.
Solvent dewaxing involves the physical fractionation of waxy components
from the hydroisomerate. Catalytic dewaxing converts a portion of the
hydroisomerate to lower boiling hydrocarbons; it often involves a
shape-selective molecular sieve, such as a zeolite or
silicoaluminophosphate material, in combination with a catalytic metal
component, such as Pt, in a fixed-bed, fluidized-bed, or slurry type
process at high temperatures and pressures in the presence of hydrogen.

[0158]Desirable GTL-derived fluids are expected to become broadly
available from several sources, including Chevron, ConocoPhillips,
ExxonMobil, Sasol, SasolChevron, Shell, Statoil, and Syntroleum.

[0159]In one embodiment, the HFA is a high purity hydrocarbon fluid
derived from a GTL process comprising a mixture of paraffins of carbon
number ranging from about C20 to C100, a molar ratio of
isoparaffins:n-paraffins greater than about 50:1, the percentage of
carbons in paraffinic structures (CP) of 98% or more, a pour point
ranging from about -20 to -60° C., and a kinematic viscosity at
100° C. ranging from about 6 to 20 cSt.

[0160]As used herein, the following terms have the indicated meanings:
"hydroisomerized" describes a catalytic process in which normal paraffins
and/or slightly branched isoparaffins are converted by rearrangement into
more branched isoparaffins (also known as "isodewaxing"); "wax" is a
hydrocarbonaceous material existing as a solid at or near room
temperature, with a melting point of 0° C. or above, and
consisting predominantly of paraffinic molecules, most of which are
normal paraffins; "slack wax" is the wax recovered from petroleum oils
such as by solvent dewaxing, and may be further hydrotreated to remove
heteroatoms.

Group III Mineral Oils

[0161]In an alternate embodiment, the HFA may be a Group III Mineral Oil
(as described in US 2008/0045638) having a flash point of 200° C.
or more and a pour point of -15° C. or less. Preferably the Group
III Mineral Oil has a saturates level of 90% or more (preferably 92% or
more, preferably 94% or more, preferably 95% or more, preferably 98% or
more); a sulfur content of less than 0.03% (preferably between 0.001 and
0.01%); and a VI of 120 or more (preferably 130 or more, preferably 140
or more). Preferably the Group III Mineral Oil has a kinematic viscosity
at 100° C. of 3 to 50, preferably 4 to 40 cSt, preferably 6 to 30
cSt, preferably 8 to 20; and/or a number average molecular weight of 300
to 5,000 g/mol, preferably 400 to 2,000 g/mol, preferably 500 to 1,000
g/mol. Preferably the Group III Mineral Oil has a pour point of
-10° C. or less, a flash point of 200° C. or more, and a
specific gravity (15.6° C./15.6° C.) of 0.86 or less.

[0162]Preferably, the Group III Mineral Oil is a Group III basestock.
Desirable Group III basestocks are commercially available from a number
of sources and include those described in the table below. The percentage
of carbons in chain-type paraffinic structures (CP) in such liquids
is greater than 80%. Chain-type paraffins (CP) are determined as
described in US 2008/0045638.

[0163]The elastomeric compositions may also contain other components and
additives customarily used in rubber compounds, such as, for example,
effective amounts of other processing aids, pigments, accelerators,
cross-linking and curing materials, antioxidants, antiozonants, fillers,
and/or clays.

[0164]The elastomeric composition may also optionally comprise at least
one filler, for example, calcium carbonate, clay, mica, silica,
silicates, talc, titanium dioxide, aluminum oxide, zinc oxide, starch,
wood flour, carbon black, or mixtures thereof. The fillers may be any
size and typically are in the range of about 0.0001 μm to about 100
μm, for example in the tire industry.

[0165]As used herein, silica is meant to refer to any type or particle
size silica or another silicic acid derivative, or silicic acid,
processed by solution, pyrogenic, or the like methods, including
untreated, precipitated silica, crystalline silica, colloidal silica,
aluminum or calcium silicates, fumed silica, and the like. Precipitated
silica can be conventional silica, semi-highly dispersible silica, or
highly dispersible silica.

[0166]The elastomeric composition may also include clay. The clay may be,
for example, montmorillonite, nontronite, beidellite, bentonite,
vokoskoite, laponite, hectorite, saponite, sauconite, magadite, kenyaite,
stevensite, vermiculite, halloysite, aluminate oxides, hydrotalcite, or
mixtures thereof. The clay may contain at least one silicate.
Alternatively, the filler may be layered clay, optionally, treated or
pre-treated with a modifying agent such as organic molecules; the layered
clay may comprise at least one silicate.

[0167]In one embodiment, the layered filler such as layered clay may
comprise at least one silicate. The silicate may comprise at least one
"smectite" or "smectite-type clay" referring to the general class of clay
minerals with expanding crystal lattices. For example, this may include
the dioctahedral smectites which consist of montmorillonite, beidellite,
and nontronite, and the trioctahedral smectites, which includes saponite,
hectorite, and sauconite. Also encompassed are synthetically prepared
smectite-clays, for example those produced by hydrothermal processes.

[0168]The layered filler such as the layered clays described above may be
modified such as intercalated or exfoliated by treatment with at least
one modifying agent. Modifying agents are also known as swelling or
exfoliating agents. Generally, they are additives capable of undergoing
ion exchange reactions with the cations present at the interlayer
surfaces of the layered filler. The modifying agent may be present in the
composition in an amount to achieve optimal air retention as measured by
the permeability testing. For example, the additive may be employed in
the range of 0.1 to 40 phr in one embodiment, or in the range of 0.2 to
20 phr, or in the range of 0.3 to 10 phr in another embodiment.

[0169]Examples of suitable exfoliating additives include, but are not
limited to, cationic surfactants such as ammonium, alkylamines or
alkylammonium (primary, secondary, tertiary and quaternary), phosphonium
or sulfonium derivatives of aliphatic, aromatic or arylaliphatic amines,
phosphines and sulfides.

[0170]The elastomeric compositions may incorporate a clay treated or
pre-treated with a modifying agent to form a nanocomposite or
nanocomposite composition. Nanocomposites may include at least one
elastomer as described above and at least one modified layered filler.
The modified layered filler may be produced by the process comprising
contacting at least one layered filler such as at least one layered clay
with at least one modifying agent.

[0171]The amount of clay or exfoliated clay incorporated in the
nanocomposite is generally that which is sufficient to develop an
improvement in the mechanical properties or barrier properties of the
nanocomposite, for example, tensile strength or oxygen permeability.
Amounts generally will be in the range of 0.5 to 10 wt % in one
embodiment, or in the range of 1 to 5 wt %, based on the polymer content
of the nanocomposite. Expressed in parts per hundred parts of rubber, the
clay or exfoliated clay may be present in the range of 1 to 30 phr, or in
the range of 5 to 20 phr.

[0172]In one embodiment, one or more, silane coupling agents are used in
the elastomeric compositions. Coupling agents are particularly desirable
when silica is the primary filler, or is present in combination with
another filler, as they help bind the silica to the elastomer. The
coupling agent may be a bifunctional organosilane crosslinking agent. An
"organosilane crosslinking agent" is any silane coupled filler and/or
crosslinking activator and/or silane reinforcing agent known to those
skilled in the art including, but not limited to, vinyl triethoxysilane,
vinyl-tris-(beta-methoxyethoxy)silane,
methacryloylpropyltrimethoxysilane, gamma-amino-propyl, triethoxysilane,
gammamercaptopropyltrimethoxysilane, and the like, and mixtures thereof.

[0173]The filler may be carbon black or modified carbon black. The filler
may also be a blend of carbon black and silica. In one embodiment, the
elastomeric composition comprises reinforcing grade carbon black at a
level in the range of 10 to 100 phr of the blend, more preferably in the
range of 30 to 80 phr in another embodiment, and in yet another
embodiment in the range of 50 to 80 phr. Useful grades of carbon black
include the ranges of from N110 to N990, preferably N660.

Crosslinking Agents, Curatives, Cure Packages, and Curing Processes

[0174]The elastomeric compositions and the articles made from those
compositions are generally manufactured with the aid of at least one cure
package, at least one curative, at least one crosslinking agent, and/or
undergo a process to cure the elastomeric composition. As used herein, at
least one curative package refers to any material or method capable of
imparting cured properties to a rubber as is commonly understood in the
industry.

[0175]Generally, polymer blends are crosslinked to improve the polymer's
mechanical properties. Physical properties, performance characteristics,
and durability of vulcanized rubber compounds are known to be related to
the number (crosslink density) and type of crosslinks formed during the
vulcanization reaction. Polymer blends may be crosslinked by adding
curative agents, for example sulfur, metals, metal oxides such as zinc
oxide, peroxides, organometallic compounds, radical initiators, fatty
acids, and other agents common in the art. Other known methods of curing
that may be used include, peroxide cure systems, resin cure systems, and
heat or radiation-induced crosslinking of polymers. Accelerators,
activators, and retarders may also be used in the curing process.

[0176]The compositions may be vulcanized (cured) by any suitable means,
such as subjecting them to heat or radiation according to any
conventional vulcanization process. The amount of heat or radiation
needed is that which is required to affect a cure in the composition, and
the invention is not herein limited by the method and amount of heat
required to cure the composition. Typically, the vulcanization is
conducted at a temperature in the range of about 100° C. to about
250° C., or in the range of about 150° C. to about
190° C., for about 1 to 150 minutes.

[0177]Halogen-containing elastomers may be crosslinked by their reaction
with metal oxides. The metal oxide is thought to react with halogen
groups in the polymer to produce an active intermediate which then reacts
further to produce carbon-carbon bonds. Zinc halide is liberated as a
by-product and it serves as an autocatalyst for this reaction. The metal
oxide can be used alone or in conjunction with its corresponding metal
fatty acid complex (e.g., zinc stearate, calcium stearate, etc.), or with
the organic and fatty acids added alone, such as stearic acid, and
optionally other curatives such as sulfur or a sulfur compound, an
alkylperoxide compound, diamines or derivatives thereof.

[0178]Sulfur is the most common chemical vulcanizing agent for
diene-containing elastomers. It exists as a rhombic 8-member ring or in
amorphous polymeric forms. The sulfur vulcanization system may consist of
an activator to activate the sulfur, an accelerator, and a retarder to
help control the rate of vulcanization. Activators are chemicals that
increase the rate of vulcanization by reacting first with the
accelerators to form rubber-soluble complexes which then react with the
sulfur to form sulfurating agents. General classes of accelerators
include amines, diamines, guanidines, thioureas, thiazoles, thiurams,
sulfenamides, sulfenimides, thiocarbamates, xanthates, and the like.

[0179]Accelerators help control the onset of and rate of vulcanization,
and the number and type of crosslinks that are formed. Retarders may be
used to delay the initial onset of cure in order to allow sufficient time
to process the unvulcanized rubber.

[0180]The acceleration of the vulcanization process may be controlled by
regulating the amount of the acceleration accelerant, often an organic
compound. The mechanism for accelerated vulcanization of natural rubber,
BR, and SBR involves complex interactions between the curative,
accelerator, activators, and polymers. Ideally, all of the available
curative is consumed in the formation of effective crosslinks which join
together two polymer chains and enhance the overall strength of the
polymer matrix. Numerous accelerators are known in the art and include,
but are not limited to, the following: stearic acid, diphenyl guanidine
(DPG), tetramethylthiuram disulfide (TMTD), benzothiazyl disulfide
(MBTS), N-tertiarybutyl-2-benzothiazole sulfenamide (TBBS),
N-cyclohexyl-2-benzothiazole-sulfenamide (CBS), and thioureas.

[0181]In one embodiment, at least one curing agent(s) is present in the
range of 0.2 to 10 phr, or 0.5 to 5 phr, or in another embodiment in the
range of 0.75 phr to 2 phr.

Processing

[0182]The elastomeric composition may be compounded (mixed) by any
conventional means known to those skilled in the art. The mixing may
occur in a single step or in multiple stages. For example, the
ingredients are typically mixed in at least two stages, namely at least
one non-productive stage followed by a productive mixing stage. The final
curatives are typically mixed in the final stage which is conventionally
called the "productive" mix stage. In the productive mix stage the mixing
typically occurs at a temperature, or ultimate temperature, lower than
the mix temperature(s) of the preceding non-productive mix stage(s). The
elastomers, polymer additives, silica and silica coupler, and carbon
black, if used, are generally mixed in one or more non-productive mix
stages. The terms "non-productive" and "productive" mix stages are well
known to those having skill in the rubber mixing art.

[0183]In one embodiment, the carbon black is added in a different stage
from zinc oxide and other cure activators and accelerators. In another
embodiment, antioxidants, antiozonants, and processing materials are
added in a stage after the carbon black has been processed with the
elastomers, and zinc oxide is added at a final stage to maximize the
compound modulus. In other embodiments, additional stages may involve
incremental additions of one or more fillers.

[0184]In another embodiment, mixing of the components may be carried out
by combining the elastomer components, filler and clay in any suitable
mixing device such as a two-roll open mill, Brabender® internal mixer,
Banbury® internal mixer with tangential rotors, Krupp internal mixer
with intermeshing rotors, or preferably a mixer/extruder, by techniques
known in the art. Mixing may be performed at temperatures up to the
melting point of the elastomer(s) used in the composition in one
embodiment, or in the range of 40° C. to 250° C. in another
embodiment, or in the range of 100° C. to 200° C. Mixing
should generally be conducted under conditions of shear sufficient to
allow the clay to exfoliate and become uniformly dispersed within the
elastomer(s) to form the nanocomposite.

[0185]Typically, from 70% to 100% of the elastomer or elastomers is first
mixed for 20 to 90 seconds, or until the temperature reaches from
40° C. to 75° C. Then, approximately 75% of the filler, and
the remaining amount of elastomer, if any, is typically added to the
mixer, and mixing continues until the temperature reaches from 90°
C. to 150° C. Next, the remaining filler is added, as well as the
processing aids, and mixing continues until the temperature reaches from
140° C. to 190° C. The masterbatch mixture is then finished
by sheeting on an open mill and allowed to cool, for example, to from
60° C. to 100° C. when curatives may be added.

[0186]Mixing with the clays is performed by techniques known to those
skilled in the art, wherein the clay is added to the polymer at the same
time as the carbon black in one embodiment. The HFA processing aid is
typically added later in the mixing cycle after the carbon black and clay
have achieved adequate dispersion in the elastomeric matrix.

[0187]The cured compositions can include various elastomers and fillers
with the HFA processing aid. The elastomeric compositions typically
include C4 to C7 monoolefin elastomers, such as
isobutylene-based elastomers, preferably halogenated
poly(isobutylene-co-p-methylstyrene), butyl rubber, with the HFA(s) being
present in the range of 2 to 40 phr in one embodiment, or 4 to 30 phr, or
4 to 15 phr, or 8 to 12 phr in another embodiment.

[0188]In one embodiment, an air barrier can be made by the method of
combining at least one random copolymer comprising a C4 to C7
isomonoolefin derived unit, at least one filler, and at least one HFA,
and at least one cure agent; and curing the combined components.

[0189]In another embodiment, an air barrier can be made by the method of
combining at least one random copolymer comprising a C4 to C7
isomonoolefin derived unit, at least one filler, and HFA having a number
average molecular weight greater than 400, and at least one cure agent;
and curing the combined components as described above.

[0190]The elastomeric compositions as described above may be used in the
manufacture of air membranes such as innerliners and innertubes used in
the production of tires. Methods and equipment used to manufacture the
innerliners and tires are well known in the art. The invention is not
limited to any particular method of manufacture for articles such as
innerliners or tires.

[0191]In one embodiment, a tire innerliner stock may be prepared by
calendering the compounded rubber composition into sheet material having
a thickness of roughly 40 to 80 mil gauge and cutting the sheet material
into strips of appropriate width and length for innerliner applications.
The innerliner stock at this stage of the manufacturing process is
typically a sticky, uncured mass and is therefore subject to deformation
and tearing as a consequence of handling and cutting operations
associated with tire construction.

[0192]The innerliner stock may then be used as an element in the
construction of a pneumatic tire. The pneumatic tire may be composed of a
layered laminate comprising an outer surface which includes the tread and
sidewall elements, an intermediate carcass layer which comprises a number
of plies containing tire reinforcing fibers, (e.g., rayon, polyester,
nylon or metal fibers) embedded in a rubbery matrix, and an innerliner
layer which is laminated to the inner surface of the carcass layer. The
tire may be built on a tire forming drum using the layers described
above. After the uncured tire has been built on the drum, the uncured
tire may be placed in a heated mold having an inflatable tire shaping
bladder to shape it and heat it to vulcanization temperatures by methods
well known in the art. Vulcanization temperatures are generally in the
range of about 100° C. to about 250° C., or preferably in
the range of 125° C. to 200° C., and the vulcanization time
may be in them range of about one minute to several hours, or more
generally in the range of about 5 to 30 minutes. Vulcanization of the
assembled tire results in vulcanization of all elements of the tire
assembly, for example, the innerliner, the carcass and the outer
tread/sidewall layers and enhances the adhesion between these elements,
resulting in a cured, unitary tire from the multi-layers.

INDUSTRIAL APPLICABILITY

[0193]The elastomeric compositions of the invention may be extruded,
compression molded, blow molded, injection molded, and laminated into
various shaped articles including fibers, films, laminates, layers,
industrial parts such as automotive parts, appliance housings, consumer
products, packaging, and the like. The elastomeric compositions are
particularly useful in air barriers, such as in pneumatic tire
components, hoses, air cushions, pneumatic springs, air bellows,
accumulator bags, and bladders for fluid retention and curing processes.

[0194]In particular, the elastomeric compositions are useful in articles
for a variety of tire applications. Such tires can be built, shaped,
molded, and cured by various methods which are known and will be readily
apparent to those having skill in the art. The elastomeric compositions
may either be fabricated into a finished article or a component of a
finished article such as an innerliner for a tire.

[0195]The elastomeric compositions of this invention are particularly
suitable for tire innerliners and innertubes and other materials
requiring good air retention. The elastomeric compositions are especially
useful for tire innerliners requiring good air impermeability and good
cold temperature properties, such as required for aircraft tires.

[0196]In preferred embodiments, the elastomeric compositions of this
invention are particularly suitable for use as tire innerliners or tire
innertubes, as they have enhanced thermal stability and physical
properties suitable for operation under severe temperature such as
required for race car tires and aircraft tires. The elastomeric
compositions possess improved low-temperature toughness without
sacrificing other advantageous traits such as improved processability and
air-impermeability.

[0197]In particular the elastomeric compositions are useful for aircraft
tires. Aircraft tires must withstand extreme conditions during service,
in particular in terms of applied load and speed, taking into account the
tire's low weight and size. Aircraft tires are subject to extreme loads
and deflections and are subject to extreme accelerations and very high
speeds particularly during landings, takeoffs and after prolonged taxiing
the tires can build up high heat all of which contribute to rapid wear.
During takeoff, very high speeds, of the order of 350 km/hr or even 450
km/hr, are achieved, and hence heating conditions exist which are also
very severe.

[0198]Aircraft tires distinguished from other tires in that they generally
require an inflation pressure greater than 9 bar (0.9 MPa) and a relative
deflection greater than 30%. The deflection of a tire is defined by the
radial deformation of the tire, or variation in the radial height of the
tire, when it changes from a non-loaded state to a statically loaded
state, under rated load and pressure conditions. It is expressed in the
form of relative deflection, which is defined by the ratio of this
variation in the radial height of the tire to half the difference between
the external diameter of the tire and the maximum diameter of the rim
measured on the hook. The external diameter of the tire is measured
statically in an non-loaded state at the rated pressure. Despite an
aircraft tire's very high inflation pressures, greater than 9 bar, their
loading or deflection during operation may commonly reach values double
those observed for heavy-vehicle tires or passenger cars.

[0199]The elastomeric compositions provided herein have improved
brittleness and impermeability properties, making them especially
suitable for use in aircraft tires. In some embodiments, there is a
synergistic effect when HFA is used allowing for the use of secondary
elastomers, such as natural rubber, at lower loading levels where the
brittleness is improved while maintaining the permeability with an
acceptable range.

[0200]In one embodiment the cured elastomeric composition has a MOCON
permeability coefficient of less than or equal to T, where
T=-0.1147Y+0.54 where Y is the change in brittleness determined by
subtracting the brittleness in ° C. of the cured elastomeric
composition containing HFA from the brittleness in ° C. of a cured
composition having the same components except that it contains a
naphthenic oil having a flash point in the range of 160 to 170°
C., a pour point of about -40° C.±5%, and a specific gravity at
15.6° C. of about 0.91±0.01 instead of the HFA. In some
embodiments, the cured elastomeric composition has a MOCON permeability
coefficient of less than or equal to T, where T=-0.1147Y+0.50, or where
T=-0.1147Y+0.45. In such embodiments, the HFA is preferably a PAO.

[0201]In another embodiment, the cured elastomeric composition has a MOCON
permeability coefficient of less than or equal to Z, where
Z=0.282X+0.4817 where X is the amount of natural rubber in phr, and has a
brittleness of less than or equal to A, where A=-0.13X-51 where X is the
amount of natural rubber in phr. In some embodiments, the cured
elastomeric composition has a MOCON permeability coefficient of less than
or equal to Z, where Z=0.0155Y+0.6187. In some embodiments, the cured
elastomeric composition has a brittleness of less than or equal to A,
where A=-0.13X-50.5, or where A=-0.13X-51.5, or where A=-0.13X-52. In
such embodiments, the cured elastomeric composition preferably comprises
a PAO.

[0202]In yet another embodiment, the cured elastomeric composition
comprises 1 to 30 phr of HFA and has a permeability that is at least 10%
less, or 15% less, or 25% less, or 30% less, or 35% less than the
permeability of a cured composition having the same components except
that it contains a naphthenic oil having a flash point in the range of
160 to 170° C., a pour point of about -40° C., and a
specific gravity at 15.6° C. of about 0.91 instead of the HFA. In
such embodiments, the HFA is preferably a PAO.

[0203]In a further embodiment, the cured elastomeric composition comprises
1 to 30 phr of HFA and has a brittleness temperature that is at least
1° C. less, or 1.5° C. less, or 2° C. less, or
3° C. less, than the brittleness temperature of a cured
composition having the same components except that it contains a
naphthenic oil having a flash point in the range of 160 to 170°
C., a pour point of about -40° C., and a specific gravity at
15.6° C. of about 0.91 instead of the HFA. In such embodiments,
the HFA is preferably a PAO.

[0204]In still another embodiment, the cured elastomeric composition
comprises 1 to 30 phr of HFA and has a brittleness temperature that is at
least 2° C. less, or 3° C. less, or 4° C. less, or
5° C. less, than the brittleness temperature of a cured
composition comprising 100 phr of BIIR, 0 phr of NR, and a naphthenic oil
having a flash point in the range of 160 to 170° C., a pour point
of about -40° C., and a specific gravity at 15.6° C. of
about 0.91 instead of the HFA. In such embodiments, the HFA is preferably
a PAO.

[0205]In some embodiments, the use of HFA instead of a naphthenic oil
reduces the Tg of the elastomeric composition. This is particularly
advantageous as a high Tg makes the materials brittle, especially at low
temperatures. The elastomeric composition comprising PAO may have a Tg
less than or equal to -45° C., or less than or equal to
-50° C., or less than or equal to -55° C.

[0206]In alternate embodiments, this invention relates to: [0207]1. A
cured elastomeric composition for use in a tire innerliner, comprising:
(a) from 50 to 100 phr of at least one isobutylene-based elastomer; (b)
less than or equal to 50 phr of natural rubber; and (c) from 1 to 30 phr
of at least one hydrocarbon fluid additive, wherein the hydrocarbon fluid
additive has a flash point of at least 200° C., a pour point of
less than or equal to -15° C., and specific gravity at
15.6° C. of less than or equal to 0.880; wherein the cured
elastomeric composition has a MOCON permeability coefficient of less than
or equal to T, where T=-0.1147Y+0.54 where Y is the change in brittleness
determined by subtracting the brittleness in ° C. of the cured
elastomeric composition containing the hydrocarbon fluid additive from
the brittleness in ° C. of a cured composition having the same
components except that it contains a naphthenic oil having a flash point
in the range of 160 to 170° C., a pour point of about -40°
C.±5%, and a specific gravity at 15.6° C. of about 0.91±0.01
instead of the hydrocarbon fluid additive. [0208]2. The composition of
paragraph 1, wherein the isobutylene-based elastomer is selected from the
group consisting of butyl rubber, halogenated butyl rubber, star-branched
butyl rubber, halogenated star-branched butyl rubber,
poly(isobutylene-co-p-methylstyrene), halogenated
poly(isobutylene-co-p-methylstyrene), and mixtures thereof. [0209]3. The
composition of paragraph 1 or 2, wherein the composition comprises less
than or equal to 10 phr of natural rubber. [0210]4. The composition of
any one of paragraphs 1 to 3, wherein the hydrocarbon fluid additive is
selected from a group consisting of polyalphaolefins, high purity
hydrocarbon fluids, water white group III mineral oils, and blends
thereof. [0211]5. The composition of any one of paragraphs 1 to 3,
wherein the hydrocarbon fluid additive is a polyalphaolefin having a
Kinematic viscosity at 100° C. of at least 4 cSt. [0212]6. The
composition of any one of paragraphs 1 to 3 or 5, wherein the hydrocarbon
fluid additive is a polyalphaolefin having a Kinematic viscosity at
100° C. in the range of 6 to 40 cSt. [0213]7. The composition of
any one of paragraphs 1 to 3, 5, or 6, wherein the hydrocarbon fluid
additive is a polyalphaolefin having a viscosity index of at least 120.
[0214]8. The composition of any one of paragraphs 1 to 7, wherein the
composition is substantially free of naphthenic oil and/or is
substantially free of aromatic oil. [0215]9. The composition of any one
of paragraphs 1 to 8, wherein the composition further comprises one or
more filler components selected from calcium carbonate, mica, silica,
silicates, talc, titanium dioxide, starch, wood flour, carbon black, and
mixtures thereof. [0216]10. The composition of any one of paragraphs 1 to
9, wherein the composition is a tire innerliner suitable for use in an
aircraft tire. [0217]11. A cured elastomeric composition for use in a
tire innerliner, comprising: (a) from 50 to 90 phr of at least one
isobutylene-based elastomer; (b) from 1 to 50 phr of natural rubber; and
(c) from 1 to 30 phr of at least one hydrocarbon fluid additive, wherein
the hydrocarbon fluid additive has a flash point of at least 200°
C., a pour point of less than or equal to -15° C., and specific
gravity at 15.6° C. of less than or equal to 0.880; wherein the
cured elastomeric composition has a MOCON permeability coefficient of
less than or equal to Z, where Z=0.282X+0.4817 where X is the amount of
natural rubber in phr, and wherein the cured elastomeric composition has
a brittleness of less than or equal to A, where A=-0.13X-51 where X is
the amount of natural rubber in phr. [0218]12. An aircraft tire
comprising an innerliner which comprises: (a) from 50 to 90 phr of at
least one isobutylene-based elastomer; (b) from 1 to 50 phr of natural
rubber; and (c) from 1 to 30 phr of at least one hydrocarbon fluid
additive, wherein the hydrocarbon fluid additive has a flash point of at
least 200° C., a pour point of less than or equal to -15°
C., and specific gravity at 15.6° C. of less than or equal to
0.880; wherein the aircraft tire has a MOCON permeability coefficient of
less than or equal to Z, where Z=0.282X+0.4817 where X is the amount of
natural rubber in phr, and wherein the cured elastomeric composition has
a brittleness of less than or equal to A, where A=-0.13X-51 where X is
the amount of natural rubber in phr. [0219]13. The composition of
paragraph 11 or 12, wherein the composition comprises from 70 to 90 phr
of the isobutylene-based elastomer. [0220]14. The composition of any one
of paragraphs 11 to 13, wherein the isobutylene-based elastomer is
selected from the group consisting of butyl rubber, halogenated butyl
rubber, star-branched butyl rubber, halogenated star-branched butyl
rubber, poly(isobutylene-co-p-methylstyrene), halogenated
poly(isobutylene-co-p-methylstyrene), and mixtures thereof. [0221]15. The
composition of any one of paragraphs 11 to 14, wherein the composition
comprises from 10 to 30 phr of natural rubber. [0222]16. The composition
of any one of paragraphs 11 to 15, wherein the hydrocarbon fluid additive
is selected from a group consisting of polyalphaolefins, high purity
hydrocarbon fluids, water white group III mineral oils, and blends
thereof. [0223]17. The composition of any one of paragraphs 11 to 15,
wherein the hydrocarbon fluid additive is a polyalphaolefin having a
Kinematic viscosity at 100° C. of at least 4 cSt. [0224]18. The
composition of any one of paragraphs 11 to 15, or 17, wherein the
hydrocarbon fluid additive is a polyalphaolefin having a Kinematic
viscosity at 100° C. in the range of 6 to 40 cSt. [0225]19. The
composition of any one of paragraphs 11 to 15, 17, or 18, wherein the
hydrocarbon fluid additive is a polyalphaolefin having a viscosity index
of at least 120. [0226]20. The composition of any one of paragraphs 11 to
19, wherein the composition is substantially free of naphthenic oil
and/or is substantially free of aromatic oil. [0227]21. The composition
of any one of paragraphs 11 to 20, wherein the composition further
comprises one or more filler components selected from calcium carbonate,
mica, silica, silicates, talc, titanium dioxide, starch, wood flour,
carbon black, and mixtures thereof. [0228]22. The composition of any one
of paragraphs 11 or 13 to 20, wherein the composition is a tire
innerliner suitable for use in an aircraft tire. [0229]23. A process for
producing an air barrier comprising the steps of: (a) combining from 50
to 90 phr of at least one isobutylene-based elastomer, from 1 to 50 phr
of natural rubber, and from 1 to 30 phr of at least one hydrocarbon fluid
additive, wherein the hydrocarbon fluid additive has a flash point of at
least 200° C., a pour point of less than or equal to -15°
C., and specific gravity at 15.6° C. of less than or equal to
0.880; (b) curing the combined components to form a cured elastomeric
composition wherein the cured elastomeric composition has a MOCON
permeability coefficient of less than or equal to Z, where
Z=0.282X+0.4817 where X is the amount of natural rubber in phr, and
wherein the cured elastomeric composition has a brittleness of less than
or equal to A, where A=-0.13X-51 where X is the amount of natural rubber
in phr; and (c) shaping the cured elastomeric composition to form the air
barrier. [0230]24. The process of paragraph 23, wherein the air barrier
is an innerliner suitable for use in an aircraft tire. [0231]25. The
composition of paragraph 23 or 24, wherein the composition comprises from
70 to 90 phr of the isobutylene-based elastomer. [0232]26. The
composition of any one of paragraphs 23 to 25, wherein the
isobutylene-based elastomer is selected from the group consisting of
butyl rubber, halogenated butyl rubber, star-branched butyl rubber,
halogenated star-branched butyl rubber,
poly(isobutylene-co-p-methylstyrene), halogenated
poly(isobutylene-co-p-methylstyrene), and mixtures thereof. [0233]27. The
composition of any one of paragraphs 23 to 26, wherein the composition
comprises from 10 to 30 phr of natural rubber. [0234]28. The composition
of any one of paragraphs 23 to 27, wherein the hydrocarbon fluid additive
is selected from a group consisting of polyalphaolefins, high purity
hydrocarbon fluids, water white group III mineral oils, and blends
thereof. [0235]29. The composition of any one of paragraphs 23 to 27,
wherein the hydrocarbon fluid additive is a polyalphaolefin having a
Kinematic viscosity at 100° C. of at least 4 cSt. [0236]30. The
composition of any one of paragraphs 23 to 27, or 29, wherein the
hydrocarbon fluid additive is a polyalphaolefin having a Kinematic
viscosity at 100° C. in the range of 6 to 40 cSt. [0237]31. The
composition of any one of paragraphs 23 to 27, 29, or 30, wherein the
hydrocarbon fluid additive is a polyalphaolefin having a viscosity index
of at least 120. [0238]32. The composition of any one of paragraphs 23 to
31, wherein the composition is substantially free of naphthenic oil
and/or is substantially free of aromatic oil. [0239]33. The composition
of any one of paragraphs 23 to 32, wherein the composition further
comprises one or more filler components selected from calcium carbonate,
mica, silica, silicates, talc, titanium dioxide, starch, wood flour,
carbon black, and mixtures thereof.

Testing Procedures

[0240]When possible, standard ASTM tests were used to determine the cured
compound physical properties. Stress/strain properties (e.g., tensile
strength, elongation at break, modulus values, energy to break) were
measured according to ASTM D412 Die C at room temperature using an
Instron 4202. Tensile strength measurements were made at ambient
temperature; the specimens (dog-bone shaped) had a restricted width of 6
mm and a restricted length of 33 mm between two tabs. Though the
thickness of the test specimen was a nominal 2.00 mm, the thickness of
the specimens varied and was measured manually by a Mitutoyo Digimatic
Indicator connected to the system computer. The specimens were pulled at
a crosshead speed of 500 mm/min and the stress/strain data was recorded.
The average stress/strain value of at least three specimens is reported.
The error (2σ) in Tensile measurements is ±0.47 MPa. The error
(2σ) in measuring 100% Modulus is ±0.11 MPa; the error
(2σ) in measuring elongation is ±13%.

[0241]Cure properties were measured using an MDR 2000 from Alpha
Technologies, Inc. at the indicated temperature and 0.5 degree arc, based
on ASTM D 5289. The values "MH" and "ML" used herein refer to "maximum
torque" and "minimum torque," respectively. The "MS" value is the Mooney
scorch value, the "ML(1+8)" value is the Mooney viscosity value of the
polymer, and the "ML(1+4)" value is the Mooney viscosity value of the
composition. The error (2σ) in the Mooney viscosity measurement is
±0.65. The values of "Tc" are cure times in minutes, and "Ts" is
scorch time in minutes.

[0242]Permeability was measured using a Mocon OxTran Model 2/61 oxygen
transmission rate test apparatus. The oxygen transmission rate is
measured under the principle of dynamic measurement of oxygen transport
through a thin film. Compound samples are clamped into a diffusion cell.
The samples are approximately 5.0 cm in diameter and about 0.5 mm thick.
The cell is then purged of residual oxygen using a high purity nitrogen
carrier gas. The nitrogen gas is routed to a sensor until a stable zero
value is established. The measurement is typically conducted at
60° C. Pure oxygen air is then introduced into the outside of the
chamber of the diffusion cell. The oxygen diffusing through the sample to
the inside chamber is conveyed to a chamber which measures the oxygen
diffusion rate. The oxygen diffusion rate is expressed as a transmission
rate coefficient. The permeation coefficient is a measure of the
transmission rate normalized for sample thickness (e.g., m) and is
expressed as a volume of gas (e.g., cc) per unit area (e.g., m2) of
the sample in a discrete unit of time (e.g., 24 hours), and has the units
of cc*mm/(m2-day). The permeability coefficient considers
atmospheric pressure and is expressed as cc*mm/(m2-day-mmHg). A
relative rating for the compound may then be obtained by comparing the
compound's permeation coefficient to that of the control compound.

[0243]Techniques for determining the molecular weight (Mn, Mw, and Mz) and
Mw/Mn (molecular weight distribution, "MWD") of the PAO are generally
described in U.S. Pat. No. 2008/0045638, which is incorporated herein by
reference.

[0244]Color is determined on the APHA scale by ASTM D 1209. Note that an
APHA color of 100 corresponds to a Saybolt color (ASTM D 156) of about
+10; an APHA color of 20 corresponds to a Saybolt color of about +25; and
an APHA color of 0 corresponds to a Saybolt color of about +30.

[0245]Carbon type composition is determined by ASTM D 2140, and gives the
percentage of aromatic carbons (CA), naphthenic carbons (CN),
and paraffinic carbons (CP) in the fluid. Specifically, CA is
the wt % of total carbon atoms in the fluid that are in aromatic
ring-type structures; CN is the wt % of total carbon atoms in the
fluid that are in saturated ring-type structures; and CP is the wt %
of total carbon atoms in the fluid that are in paraffinic chain-type
structures. ASTM D 2140 involves calculating a "Viscosity Gravity
Constant" (VGC) and "Refractivity Intercept" (RI) for the fluid, and
determining the carbon type composition from a correlation based on these
two values. However, this method is known to fail for highly paraffinic
oils, because the VGC and RI values fall outside the correlation range.
Therefore, for purposes of this invention, the following protocol is
used: If the calculated VGC (ASTM D 2140) for a fluid is 0.800 or
greater, the carbon type composition including CP is determined by
ASTM D 2140. If the calculated VGC (ASTM D 2140) is less than 0.800, the
fluid is considered to have CP of at least 80%. If the calculated
VGC (ASTM D 2140) is less than 0.800 but greater than 0.765, then ASTM D
3238 is used to determine the carbon type composition including CP.
If application of ASTM D 3238 yields unphysical quantities (e.g., a
negative CA value), then CP is defined to be 100%. If the
calculated VGC (ASTM D 2140) for a fluid is 0.765 or less, then CP
is defined to be 100%.

[0247]Testing procedures not described herein are described in US
2008/0045638, which is incorporated by reference herein.

EXAMPLES

[0248]Elastomeric compositions comprising at least one isobutylene-based
elastomer and at least one PAO will now be further described with
reference to the following non-limiting examples. The test methods used
in the Examples are as described above. The PAOs used in the examples
were prepared with either BF3 or AlCl3 catalyst systems. Table
2 lists typical physical and chemical properties of the various PAOs used
in the examples. A listing of the various other components used in the
elastomeric compositions of the examples is in Table 3.

[0249]Various PAOs were evaluated as process aids in model tire innerliner
compounds. Naphthenic oil is typically used in such compounds at 8 phr.
In the compounds of Example 1, PAO was either mixed with naphthenic oil
or replaced the naphthenic oil. The compound formulations are listed in
Table 4, all amounts listed are in phr. The compounds were mixed in a 1 L
Banbury mixer using a 2-stage mixing procedure. The vulcanization system
(Kadoz 911, MBTS, and Sulfur) were added in the second stage. The
compounds were tested for a range of processing, curing, and physical
properties. The data is presented in Table 5.

[0250]Typically, a compound viscosity in the range of 50 to 60 MU, a
tensile strength in the range of 9 to 11 MPa, an elongation at break of
greater than 700%, and a 300% modulus of 4 MPa or less are desirable to
ensure adequate processing qualities in a factory and adequate
performance in a tire. As seen in Table 5, the compounds of Example 1
where the PAOs have been mixed with naphthenic oil or have replaced the
naphthenic oil had comparable compound properties to Compound 1, which
contained only naphthenic oil.

Example 2

[0251]In Example 2, model tire innerliner compounds were made which
contained varying amounts of halogenated butyl rubber and natural rubber.
PAO-A and PAO-B were used to replace the naphthenic oil which would
typically be used in the compounds. The compound formulations are listed
in Table 6, all amounts listed are in phr. The compounds were tested for
a range of processing, curing, and physical properties, with the results
listed in Table 7.

[0252]In Example 3, model tire innerliner compounds were made which
contained varying amounts of halogenated butyl rubber and natural rubber.
PAO-A and PAO-B were used to replace the naphthenic oil which would
typically be used in the compounds. The compound formulations are listed
in Table 8, all amounts listed are in phr. The compounds were tested for
a range of processing, curing, and physical properties, with the results
listed in Table 9.

[0253]As seen in Example 2 and 3, the brittleness temperature was lowered
by the addition of the PAO at all levels, no matter what level of
halobutyl the composition contained. The brittle point of a 100 phr
halobutyl recipe with PAO was lowered to the level of a 80 phr recipe
without PAO. The brittle point of an 80 phr halobutyl 20 phr natural
rubber with PAO was lowered to the level of a 60 phr halobutyl 40 phr
natural rubber recipe without PAO. The permeability of the 80 phr
halobutyl recipe was improved with the addition of up to 12 phr of PAO.

[0254]The data from the Examples was used to create FIGS. 1, 2, and 3.

[0255]All priority documents, patents, publications, and patent
applications, test procedures (such as ASTM methods), and other documents
cited herein are fully incorporated by reference to the extent such
disclosure is not inconsistent with this invention and for all
jurisdictions in which such incorporation is permitted.

[0256]When numerical lower limits and numerical upper limits are listed
herein, ranges from any lower limit to any upper limit are contemplated.

[0257]While the illustrative embodiments of the invention have been
described with particularity, it will be understood that various other
modifications will be apparent to and can be readily made by those
skilled in the art without departing from the spirit and scope of the
invention. Accordingly, it is not intended that the scope of the claims
appended hereto be limited to the examples and descriptions set forth
herein but rather that the claims be construed as encompassing all the
features of patentable novelty which reside in the present invention,
including all features which would be treated as equivalents thereof by
those skilled in the art to which the invention pertains.